Microreactor and method of producing the same

ABSTRACT

A microreactor is configured to have a metal substrate having a microchannel portion on one surface thereof, a heater provided on the other surface of the metal substrate via an insulating film, a catalyst supported on the microchannel portion, and a cover member having a feed material inlet and a gas outlet and joined to the metal substrate so as to cover the microchannel portion. Since the microreactor uses the metal substrate having a high thermal conductivity and a small heat capacity, the efficiency of heat conduction from the heater to the supported catalyst becomes high, and the processing of the metal substrate is easy to facilitate the production.

TECHNICAL FIELD

The present invention relates to a microreactor for use in a reformerfor hydrogen production and, in particular, to a microreactor forobtaining hydrogen gas by reforming a feed material such as methanol,and a production method of such a microreactor.

BACKGROUND ART

In recent years, attention has been paid to using hydrogen as fuelbecause of no generation of global warming gas such as carbon dioxide interms of the global environmental protection, and of the high energyefficiency. Particularly, attention has been paid to fuel cells becausethey can directly convert hydrogen to electric power and enable the highenergy conversion efficiency in the cogeneration system utilizinggenerated heat. The fuel cells have been hitherto employed under theparticular conditions such as in the space development and the oceandevelopment. Recently, however, the development has advanced towardusing them for automobile and household distributed power supplies, andfuel cells for portable devices have also been developed.

Among the fuel cells, the fuel cell for producing electricity byelectrochemically reacting hydrogen gas obtained by reforminghydrocarbon fuel such as natural gas, gasoline, butane gas, or methanol,and oxygen in air is composed of a reformer for producing hydrogen gasby, in general, steam reforming hydrocarbon fuel, a fuel cell body forproducing electricity, and so forth.

In the reformer for obtaining hydrogen gas by steam reforming methanolor the like as a feed material, a Cu—Zn catalyst is mainly used to carryout steam reforming of the feed material by an endothermic reaction. Inthe industrial fuel cell, since the startup and stop are not frequentlycarried out, a temperature fluctuation of the reformer is not liable tooccur. However, in the fuel cell for automobile or portable device,since the startup and stop are carried out frequently, the reformer isrequired to rise up quickly (a time for reaching a steam reformingtemperature of methanol is short) upon starting up from the stoppedstate.

On the other hand, particularly for the portable device, reduction insize of the fuel cell is essential so that reduction in size of thereformer has been studied variously. For example, there has beendeveloped a microreactor having a silicon substrate or a ceramicsubstrate formed with a microchannel portion and carrying a catalyst inthis microchannel portion (Laid-open Unexamined Patent Publication No.2002-252014).

In the conventional microreactor, however, there has been a problem thatthe heat utilization efficiency is low so that the rising speed of thereformer is slow upon starting up from the stopped state. There has alsobeen a problem that processing by a micromachine, etc. are required andtherefore the production cost is high. Further, a space allowed for themicroreactor is strictly limited in the fuel cell for portable device sothat further reduction in size has been strongly demanded.

Further, the conventional microreactor has a low reaction efficiency andtherefore a microreactor with a higher reaction efficiency has beendemanded. Moreover, in the conventional microreactor, there has alsobeen a problem that there is possibility of a catalyst to be deactivatedby heat in the production stage, and therefore, a usable catalyst islimited and the production process management is difficult.

Furthermore, in the hydrogen production by the conventionalmicroreactors, the microreactor is prepared for each of processes(mixing, reforming, CO removal) of the hydrogen production, and theseplurality of microreactors are connected by piping, and therefore, arequired space becomes large, which has seriously impeded the sizereduction when a space allowed for the microreactors is strictly limitedlike in case of the fuel cell for portable device.

There has been a problem that when a catalyst is subjected todeactivation or degradation to lose its function in the microreactor forone process while being used, it is necessary to exchange the whole ofthe plurality of microreactors including the normally functioningmicroreactors, so that reduction in running cost is impeded.

DISCLOSURE OF THE INVENTION

Therefore, the present invention has been made for solving the foregoingproblems. An object thereof is to provide a microreactor that enables asmall-sized and highly-efficient reformer for hydrogen production, and aproduction method that can easily produce such a microreactor.

For accomplishing such an object, the present invention is configuredsuch that a microreactor for obtaining hydrogen gas by reforming a feedmaterial, comprises a metal substrate having a microchannel portion onone surface thereof, a heater provided on the other surface of saidmetal substrate via an insulating film, a catalyst supported on saidmicrochannel portion, and a cover member having a feed material inletand a gas outlet and joined to said metal substrate so as to cover saidmicrochannel portion.

Further, the present invention is configured such that a productionmethod of a microreactor for obtaining hydrogen gas by reforming a feedmaterial, comprises a step of forming a microchannel portion on onesurface of a metal substrate; a step of anodically oxidizing said metalsubstrate to form an insulating film in the form of a metal oxide film;a step of providing a heater on said metal oxide film on a surface,where said microchannel portion is not formed, of said metal substrate;a step of applying a catalyst to said microchannel portion; and a stepof joining a cover member formed with a feed material inlet and a gasoutlet to said metal substrate so as to cover said microchannel portion.

Further, the present invention is configured such that a productionmethod of a microreactor for obtaining hydrogen gas by reforming a feedmaterial, comprises a step of forming a microchannel portion on onesurface of a metal substrate; a step of providing an insulating film ona surface, where said microchannel portion is not formed, of said metalsubstrate; a step of providing a heater on said insulating film; a stepof applying a catalyst to said microchannel portion; and a step ofjoining a cover member formed with a feed material inlet and a gasoutlet to said metal substrate so as to cover said microchannel portion.

Further, the present invention is configured such that a productionmethod of a microreactor for obtaining hydrogen gas by reforming a feedmaterial, comprises a step of forming a microchannel portion on onesurface of a metal substrate; a step of anodically oxidizing said metalsubstrate to form an insulating film in the form of a metal oxide film;a step of applying a catalyst to said microchannel portion; a step ofjoining a cover member formed with a feed material inlet and a gasoutlet to said metal substrate so as to cover said microchannel portion;and a step of providing a heater on said metal oxide film on a surface,where said microchannel portion is not formed, of said metal substrate.

Further, the present invention is configured such that a productionmethod of a microreactor for obtaining hydrogen gas by reforming a feedmaterial, comprises a step of forming a microchannel portion on onesurface of a metal substrate; a step of applying a catalyst to saidmicrochannel portion; a step of joining a cover member formed with afeed material inlet and a gas outlet to said metal substrate so as tocover said microchannel portion; a step of providing an insulating filmon a surface, where said microchannel portion is not formed, of saidmetal substrate; and a step of providing a heater on said insulatingfilm.

According to the foregoing present invention, since the metal substrateforming the microreactor has a higher thermal conductivity and a smallerheat capacity as compared with a silicon substrate or a ceramicsubstrate, heat is transmitted from the heater to the applied catalystwith a high efficiency, so that there is enabled a reformer for hydrogenproduction wherein the rising is fast upon starting up from the stoppedstate and the utilization efficiency of the input power to the heater ishigh. Further, the formation of the microchannel portion on the metalsubstrate does not require the processing by a micromachine, but can beeasily implemented by a low-priced processing method such as etching tothereby enable reduction in production cost of the microreactor.

Further, the present invention is configured such that, in amicroreactor for obtaining hydrogen gas by reforming a feed material, aplurality of metal substrates each having on one surface thereof amicrochannel portion carrying a catalyst are stacked in multi-steps sothat the surfaces where said microchannel portions are formed areoriented in the same direction, said metal substrates are provided withthrough holes, respectively, for communication between said microchannelportions of the metal substrates in the respective steps, at least oneof said metal substrates is provided with a heater that is disposed, viaan insulating film, on a surface where said microchannel portion is notformed, and a cover member having a gas outlet is joined to said metalsubstrate located at an outermost position of the multi-steps andexposing said microchannel portion.

Further, the present invention is configured such that a productionmethod of a microreactor for obtaining hydrogen gas by reforming a feedmaterial, comprises a step of forming, on one surface of each of aplurality of metal substrates, a microchannel portion and a through holehaving an opening at a predetermined position of said microchannelportion; a step of anodically oxidizing said metal substrates to forminsulating films each in the form of a metal oxide film; a step ofproviding a heater on said metal oxide film on a surface, where saidmicrochannel portion is not formed, of at least one of said metalsubstrates; a step of applying catalysts to the microchannel portions ofsaid plurality of metal substrates; a step of removing said metal oxidefilm at a portion subjected to joining when said plurality of metalsubstrates are stacked in multi-steps; and a step of joining togethersaid plurality of metal substrates so as to be stacked in multi-stepssuch that the microchannel portions of said metal substrates communicatewith each other via said through holes, and joining a cover memberformed with a gas outlet to said metal substrate located at an outermostposition of the multi-steps and exposing said microchannel portion.

Further, the present invention is configured such that a productionmethod of a microreactor for obtaining hydrogen gas by reforming a feedmaterial, comprises a step of forming, on one surface of each of aplurality of metal substrates, a microchannel portion and a through holehaving an opening at a predetermined position of said microchannelportion; a step of providing an insulating film on a surface, where saidmicrochannel portion is not formed, of each of said metal substrates; astep of providing a heater on said insulating film of at least one ofsaid metal substrates; a step of applying catalysts to the microchannelportions of said plurality of metal substrates; and a step of joiningtogether said plurality of metal substrates so as to be stacked inmulti-steps such that the microchannel portions of said metal substratescommunicate with each other via said through holes, and joining a covermember formed with a gas outlet to said metal substrate located at anoutermost position of the multi-steps and exposing said microchannelportion.

Further, the present invention is configured such that a productionmethod of a microreactor for obtaining hydrogen gas by reforming a feedmaterial, comprises a step of forming, on one surface of each of aplurality of metal substrates, a microchannel portion and a through holehaving an opening at a predetermined position of said microchannelportion; a step of anodically oxidizing said metal substrates to forminsulating films each in the form of a metal oxide film; a step ofapplying catalysts to the microchannel portions of said plurality ofmetal substrates; a step of removing said metal oxide film at a portionsubjected to joining when said plurality of metal substrates are stackedin multi-steps; a step of joining together said plurality of metalsubstrates so as to be stacked in multi-steps such that the microchannelportions of said metal substrates communicate with each other via saidthrough holes, and joining a cover member formed with a gas outlet tosaid metal substrate located at an outermost position of the multi-stepsand exposing said microchannel portion; and a step of providing a heateron at least one of said metal oxide films located at an outermostposition of the multi-steps.

Further, the present invention is configured such that a productionmethod of a microreactor for obtaining hydrogen gas by reforming a feedmaterial, comprises a step of forming, on one surface of each of aplurality of metal substrates, a microchannel portion and a through holehaving an opening at a predetermined position of said microchannelportion; a step of applying catalysts to the microchannel portions ofsaid plurality of metal substrates; a step of joining together saidplurality of metal substrates so as to be stacked in multi-steps suchthat the microchannel portions of said metal substrates communicate witheach other via said through holes, and joining a cover member formedwith a gas outlet to said metal substrate located at an outermostposition of the multi-steps and exposing said microchannel portion; anda step of providing an insulating film on a surface of at least one ofsaid metal substrates located at an outermost position of themulti-steps, and providing a heater on said insulating film.

According to the foregoing present invention, mixing of feed materials,vaporization thereof, reforming of mixture gas, and removal ofimpurities can be performed in the microchannel portions, carrying thecatalysts, of the metal substrates stacked in multi-steps, so that highpurity hydrogen gas can be obtained from the gas outlet of the covermember. Therefore, there is enabled a reformer for hydrogen productionwith a higher space efficiency as compared with a case where a pluralityof microreactors are connected by connecting pipes. Further, since themetal substrate forming the microreactor has a higher thermalconductivity and a smaller heat capacity as compared with a siliconsubstrate or a ceramic substrate, heat is transmitted from the heater tothe applied catalyst with a high efficiency, so that there is enabled areformer for hydrogen production wherein the rising is fast uponstarting up from the stopped state and the utilization efficiency of theinput power to the heater is high. Further, the formation of themicrochannel portion on the metal substrate does not require theprocessing by a micromachine, but can be easily implemented by alow-priced processing method such as etching to thereby enable reductionin production cost of the microreactor.

Further, the present invention is configured such that a microreactorfor obtaining hydrogen gas by reforming a feed material, comprises ajoined body comprising a metal substrate provided with a microchannelportion on one surface thereof, and a metal cover member having a feedmaterial inlet and a gas outlet and joined to said metal substrate so asto cover said microchannel portion, a flow path formed by saidmicrochannel portion located inside said joined body and said metalcover member, and a catalyst supported on a whole inner wall surface ofsaid flow path.

Further, the present invention is configured such that a microreactorfor obtaining hydrogen gas by reforming a feed material, comprises ajoined body formed by joining together a pair of metal substrates eachhaving a microchannel portion on one surface thereof and having patternsof said microchannel portions that are in a plane symmetricalrelationship to each other, such that said microchannel portionsconfront each other, a flow path formed by said microchannel portionsconfronting each other. inside said joined body, a catalyst supported ona whole inner wall surface of said flow path, a feed material inletlocated at one end portion of said flow path, and a gas outlet locatedat the other end portion of said flow path.

Further, the present invention is configured such that a productionmethod of a microreactor for obtaining hydrogen gas by reforming a feedmaterial, comprises a channel portion forming step of forming amicrochannel portion on one surface of a metal substrate; a joining stepof joining a metal cover member having a feed material inlet and a gasoutlet to said metal substrate so as to cover said microchannel portionto thereby form a joined body having a flow path; a surface processingstep of forming a metal oxide film on an inner wall surface of said flowpath; and a catalyst applying step of applying a catalyst to the innerwall surface of said flow path via said metal oxide film.

Further, the present invention is configured such that a productionmethod of a microreactor for obtaining hydrogen gas by reforming a feedmaterial, comprises a channel portion forming step of formingmicrochannel portions with patterns that are plane-symmetrical with eachother, on either surfaces of a pair of metal substrates; a joining stepof joining together said pair of metal substrates so that saidmicrochannel portions confront each other, to thereby form a joined bodyhaving a flow path; a surface processing step of forming a metal oxidefilm on an inner wall surface of said flow path; and a catalyst applyingstep of applying a catalyst to the inner wall surface of said flow pathvia said metal oxide film.

Further, the present invention is configured such that a productionmethod of a microreactor for obtaining hydrogen gas by reforming a feedmaterial, comprises a channel portion forming step of forming amicrochannel portion on one surface of a metal substrate; a surfaceprocessing step of forming a metal oxide film on an inner wall surfaceof said microchannel portion; a joining step of joining a metal covermember having a feed material inlet and a gas outlet to said metalsubstrate so as to cover said microchannel portion to thereby form ajoined body having a flow path; and a catalyst applying step of applyinga catalyst to an inner wall surface of said flow path via said metaloxide film.

Further, the present invention is configured such that a productionmethod of a microreactor for obtaining hydrogen gas by reforming a feedmaterial, comprises a channel portion forming step of formingmicrochannel portions with patterns that are plane-symmetrical with eachother, on either surfaces of a pair of metal substrates; a surfaceprocessing step of forming a metal oxide film on an inner wall surfaceof each microchannel portion; a joining step of joining together saidpair of metal substrates so that said microchannel portions confronteach other, to thereby form a joined body having a flow path; and acatalyst applying step of applying a catalyst to an inner wall surfaceof said flow path via said metal oxide film.

According to the foregoing present invention, since the catalyst issupported on the whole inner wall surface of the flow path, the reactionarea is increased to thereby improve a reaction efficiency so thateffective utilization of a space is made possible. Further, since themetal substrate forming the microreactor has a higher thermalconductivity and a smaller heat capacity as compared with a siliconsubstrate or a ceramic substrate, heat is transmitted from the heater tothe applied catalyst with a high efficiency, so that there is enabled areformer for hydrogen production wherein the rising is fast uponstarting up from the stopped state and the utilization efficiency of theinput power to the heater is high.

Further, since the catalyst is applied after the joined body having theflow path therein is formed in the joining process, there is nopossibility of deactivation of the catalyst due to heat in the joiningprocess so that the selection width of the catalyst is broadened.Further, by preparing a plurality of joined bodies through completion upto the joining process and applying desired catalysts to these joinedbodies, it is possible to produce microreactors to be used in differentreactions, for example, microreactors for reforming methanol and foroxidation of carbon monoxide depending on uses, and therefore,simplification of the production processes is made possible. Further,the formation of the microchannel portion on the metal substrate doesnot require the processing by a micromachine, but can be easilyimplemented by a low-priced processing method such as etching, andfurther, the polishing process is also unnecessary, so that reduction inproduction cost of the microreactor can be achieved. Further, if it isconfigured such that no angular portion exists on the inner wall surfaceof the flow path, dispersion of the applying amount in the catalystapplying process is suppressed so that the catalyst can be uniformlyapplied.

Further, the present invention is configured such that a microreactorfor obtaining hydrogen gas by reforming a feed material, comprises atleast a plurality of unit flow path members each having a flow pathinside, said flow path having one end portion serving as an inlet andthe other end portion serving as an outlet, and a coupling memberretaining said unit flow path members in a multi-step state, whereinsaid coupling member comprises a plurality of coupling portions fortightly retaining the unit flow path members at positions where theinlets of the unit flow path members are located and at positions wherethe outlets thereof are located, a feed material inlet, and a gasoutlet, wherein at least one of said unit flow path members is a unitmicroreactor carrying a catalyst in said flow path, and wherein a feedmaterial is introduced from the feed material inlet of said couplingmember, and a predetermined reaction is carried out in said unitmicroreactor in said plurality of unit flow path members to therebyobtain desired produced gas from the gas outlet of said coupling member.

According to the foregoing present invention, in the unit flow pathmembers coupled and retained together in the multi-step state, thedesired unit flow path member is selected to be the unit microreactorapplying the catalyst to the flow path. Therefore, the space utilizationefficiency is improved and, depending on selection of the number ofsteps of unit microreactors and kinds of catalysts to be applied to theunit microreactors, there is enabled a microreactor for hydrogenproduction having desired performance and property. Further, by makingeach unit flow path member detachable, it is possible to maintain thefunction of the microreactor as a whole by exchanging only such a unitmicroreactor suffering deactivation or degradation of a catalyst.Further, by allowing a catalyst to be applied after formation of ajoined body to constitute a unit microreactor, it becomes possible touse unit flow path members (joined bodies) of the same structure andincorporate a unit microreactor carrying a catalyst satisfying arequired function, which enables reduction in production cost andrunning cost of the microreactor. Further, by providing a heater in adesired unit microreactor, or interposing a gap for thermal insulationor a heat insulating material between unit flow path members, an optimumtemperature can be ensured per unit microreactor so that improvement inreaction efficiency and effective utilization of heat are made possible.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing one embodiment of a microreactor ofthe present invention.

FIG. 2 is an enlarged longitudinal sectional view of the microreactorshown in FIG. 1, taken along line II-II.

FIG. 3 is a perspective view showing the side, where a microchannelportion is formed, of a metal substrate of the microreactor shown inFIG. 1.

FIG. 4 is a longitudinal sectional view, corresponding to FIG. 2,showing another embodiment of a microreactor of the present invention.

FIG. 5 is a perspective view showing one embodiment of a microreactor ofthe present invention.

FIG. 6 is an enlarged longitudinal sectional view of the microreactorshown in FIG. 5, taken along line II-II.

FIG. 7 is an enlarged longitudinal sectional view of the microreactorshown in FIG. 5, taken along line III-III.

FIG. 8 is a perspective view showing the state where a heater protectivelayer 7 is peeled off in the microreactor 1 shown in FIG. 5.

FIG. 9 is a perspective view showing the side, where a microchannelportion is formed, of a first-step metal substrate of the microreactorshown in FIG. 5.

FIG. 10 is a perspective view showing the side, where a microchannelportion is formed, of a second-step metal substrate of the microreactorshown in FIG. 5.

FIG. 11 is a longitudinal sectional view, corresponding to FIG. 6,showing another embodiment of a microreactor of the present invention.

FIG. 12 is a perspective view showing one embodiment of a microreactorof the present invention.

FIG. 13 is an enlarged longitudinal sectional view of the microreactorshown in FIG. 12, taken along line A-A.

FIG. 14 is a perspective view showing the side, where a microchannelportion is formed, of a metal substrate forming the microreactor shownin FIG. 12.

FIG. 15 is a longitudinal sectional view, corresponding to FIG. 13,showing another embodiment of a microreactor of the present invention.

FIG. 16 is a perspective view showing another embodiment of amicroreactor of the present invention.

FIG. 17 is an enlarged longitudinal sectional view of the microreactorshown in FIG. 16, taken along line B-B.

FIG. 18 is a perspective view showing the side, where a microchannelportion is formed, of each of metal substrates forming the microreactorshown in FIG. 16.

FIG. 19 is a longitudinal sectional view, corresponding to FIG. 17,showing another embodiment of a microreactor of the present invention.

FIG. 20 is a perspective view showing one embodiment of a microreactorof the present invention.

FIG. 21 is an enlarged longitudinal sectional view of the microreactorshown in FIG. 20, taken along line I-I.

FIG. 22 is a perspective view showing the state where constituentmembers of the microreactor shown in FIG. 20 are separated from eachother.

FIG. 23 is a perspective view for describing an example of a flow pathwithin a unit flow path member forming the microreactor of the presentinvention.

FIG. 24 is a diagram showing the side, where coupling portions areformed, of a coupling member.

FIG. 25 is a sectional view of the coupling member shown in FIG. 24,wherein FIG. 25A is a sectional view taken along line II-II and FIG. 25Bis a sectional view taken along line III-III.

FIG. 26 is a longitudinal sectional view, corresponding to FIG. 21, fordescribing another example of a microreactor of the present invention.

FIG. 27 is a longitudinal sectional view showing other examples of aunit flow path member (unit microreactor) forming the microreactor ofthe present invention.

FIG. 28 is a process diagram showing one example of a production methodof a unit microreactor.

FIG. 29 is a process diagram showing another example of a productionmethod of a unit microreactor.

FIGS. 30A to 30D are process diagrams for describing one embodiment of amicroreactor producing method of the present invention.

FIGS. 31A to 31C are process diagrams for describing one embodiment of amicroreactor producing method of the present invention.

FIGS. 32A to 32D are process diagrams for describing another embodimentof a microreactor producing method of the present invention.

FIGS. 33A to 33C are process diagrams for describing another embodimentof a microreactor producing method of the present invention.

FIGS. 34A to 34D are process diagrams for describing one embodiment of amicroreactor producing method of the present invention.

FIGS. 35A to 35D are process diagrams for describing one embodiment of amicroreactor producing method of the present invention.

FIGS. 36A to 36D are process diagrams for describing one embodiment of amicroreactor producing method of the present invention.

FIGS. 37A to 37D are process diagrams for describing one embodiment of amicroreactor producing method of the present invention.

FIGS. 38A to 38D are process diagrams for describing one embodiment of amicroreactor producing method of the present invention.

FIGS. 39A to 39D are process diagrams for describing another embodimentof a microreactor producing method of the present invention.

FIGS. 40A to 40D ate process diagrams for describing another embodimentof a microreactor producing method of the present invention.

FIGS. 41A to 41C are process diagrams for describing one embodiment of amicroreactor producing method of the present invention.

FIGS. 42A to 42C are process diagrams for describing one embodiment of amicroreactor producing method of the present invention.

FIGS. 43A to 43C are process diagrams for describing another embodimentof a microreactor producing method of the present invention.

FIGS. 44A to 44C are process diagrams for describing another embodimentof a microreactor producing method of the present invention.

FIGS. 45A to 45C are process diagrams for describing another embodimentof a microreactor producing method of the present invention.

FIGS. 46A to 46C are process diagrams for describing another embodimentof a microreactor producing method of the present invention.

FIGS. 47A to 47C are process diagrams for describing another embodimentof a microreactor producing method of the present invention.

FIGS. 48A to 48C are process diagrams for describing another embodimentof a microreactor producing method of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinbelow, embodiments of the present invention will be described withreference to the drawings.

[Microreactor]

First, a microreactor of the present invention will be described.

First Embodiment of Microreactor

FIG. 1 is a perspective view showing one embodiment of the microreactorof the present invention, and FIG. 2 is an enlarged longitudinalsectional view of the microreactor shown in FIG. 1, taken along lineII-II. In FIGS. 1 and 2, the microreactor 1 of the present inventioncomprises a metal substrate 2, a microchannel portion 3 formed on onesurface 2 a of the metal substrate 2, an insulating film 4 in the formof a metal oxide film formed on the inside of the microchannel portion 3and on both surfaces 2 a and 2 b and side surfaces 2 c of the metalsubstrate 2, a heater 5 provided on the surface 2 b of the metalsubstrate 2 via the insulating film 4, a catalyst C supported on themicrochannel portion 3, and a cover member 8 joined to the metalsubstrate 2 so as to cover the foregoing microchannel portion 3. Theheater 5 is formed with electrodes 6 and 6, and a heater protectivelayer 7 having electrode opening portions 7 a and 7 a for exposing theelectrodes 6 and 6 is provided so as to cover the heater 5. Further, theforegoing cover member 8 is provided with a feed material inlet 8 a anda gas outlet 8 b.

FIG. 3 is a perspective view showing the side, where the microchannelportion 3 is formed, of the metal substrate 2 of the microreactor 1shown in FIG. 1. As shown in FIG. 3, the microchannel portion 3 isformed so as to leave comb-shaped ribs 2A and 2B and has a shape that iscontinuous from an end portion 3 a to an end portion 3 b. By locatingthe feed material inlet 8 a of the cover member 8 at the end portion 3 aand the gas outlet 8 b at the end portion 3 b, there is formed a flowpath that is continuous from the feed material inlet 8 a to the gasoutlet 8 b.

For the metal substrate 2 forming the microreactor 1 of the presentinvention, there can be used such metal that can form the metal oxidefilm (insulating film 4) by anodic oxidation. As such metal, there canbe cited, for example, Al, Si, Ta, Nb, V, Bi, Y, W, Mo, Zr, Hf, or thelike. Among these metals, particularly Al is preferably used in terms ofprocessing suitability, properties such as a heat capacity and a thermalconductivity, and a unit price. The thickness of the metal substrate 2can be suitably set taking into account the size of the microreactor 1,properties such as a heat capacity and a thermal conductivity of metalto be used, the size of the microchannel portion 3 to be formed, and soforth. For example, it can be set within a range of about 50 to 2000 μm.

The formation of the metal oxide film (insulating film 4) by anodicoxidation on the metal substrate 2 can be implemented by, in the statewhere the metal substrate 2 is connected to an anode as an externalelectrode, immersing the metal substrate 2 in an anode oxidizingsolution so as to confront a cathode and energizing it. The thickness ofthe metal oxide film (insulating film 4) can be set within a range of,for example, about 5 to 150 μm.

The microchannel portion 3 formed on the metal substrate 2 is notlimited to the shape as shown in FIG. 3, but can be formed into adesirable shape like one wherein an amount of the catalyst C supportedon the microchannel portion 3 increases and the flow path length inwhich a feed material contacts with the catalyst C is prolonged.Normally, the depth of the microchannel portion 3 can be set within arange of about 100 to 1000 μm, the width thereof can be set within arange of about 100 to 1000 μm, and the flow path length thereof can fallwithin a range of about 30 to 300 mm.

In the present invention, since the insulating film 4 in the form of themetal oxide film is formed also on the inside of the microchannelportion 3, a applying amount of the catalyst C is increased to enablestable catalyst applying due to a surface structure of the metal oxidefilm having microholes.

As the catalyst C, it is possible to use a known catalyst that hasconventionally been employed for steam reforming.

The heater 5 forming the microreactor 1 of the present invention is forsupplying heat required for steam heating of the feed material, which isan endothermic reaction, and it is possible to use therefor a materialsuch as carbon paste, nichrome (Ni—Cr alloy), W (tungsten), or Mo(molybdenum). The heater 5 can have a shape like one that is obtainedby, for example, drawing a fine line having a width of about 10 to 200μm over the whole of a region on the metal substrate surface 2 b(insulating film 4) corresponding to a region where the microchannelportion 3 is formed.

Such a heater 5 is formed with the electrodes 6 and 6 for energization.The electrodes 6 and 6 for energization can be formed using a conductivematerial such as Au, Ag, Pd, or Pd—Ag.

The heater protective layer 7 has the electrode opening portions 7 a and7 b for exposing the foregoing electrodes 6 and 6 and is disposed so asto cover the heater 5. The heater protective layer 7 can be formed of,for example, photosensitive polyimide, polyimide varnish, or the like.The thickness of the heater protective layer 7 can be suitably settaking into account a material to be used and so forth. For example, itcan be set within a range of about 2 to 25 μm.

For the cover member 8 forming the microreactor 1 of the presentinvention, an Al alloy, a Cu alloy, a stainless material, or the likecan be used. The thickness of the cover member 8 can be suitably settaking into account a material to be used and so forth. For example, itcan be set within a range of about 20 to 200 μm. The feed material inlet8 a and the gas outlet 8 b of the cover member 8 are provided so as tobe located at both end portions 3 a and 3 b of the flow path of themicrochannel portion 3 formed on the metal substrate 2.

Second Embodiment of Microreactor

FIG. 4 is a longitudinal sectional view, corresponding to FIG. 2,showing another embodiment of the microreactor of the present invention.In FIG. 4, the microreactor 1′ of the present invention comprises ametal substrate 2′, a microchannel portion 3 formed on one surface 2′aof the metal substrate 2′, an insulating film 4′ formed on the othersurface 2′b of the metal substrate 2′, a heater 5 provided on thesurface 2′b of the metal substrate 2′ via the insulating film 4′, acatalyst C supported on the microchannel portion 3, and a cover member 8joined to the metal substrate 2′ so as to cover the foregoingmicrochannel portion 3. The heater 5 is formed with electrodes 6 and 6,and a heater protective layer 7 having electrode opening portions 7 aand 7 a for exposing the electrodes 6 and 6 is provided so as to coverthe heater 5. Further, the foregoing cover member 8 is provided with afeed material inlet 8 a and a gas outlet 8 b.

Such a microreactor 1′ is the same as the foregoing microreactor 1except that the metal member 2′ and the insulating layer 4′ aredifferent and that the metal oxide film (insulating layer 4) is notformed in the microchannel portion 3, and therefore, the sameconstituent members are assigned the same member numerals to omitdescription thereof.

As the metal substrate 2′ forming the microreactor 1′ of the presentinvention, use can be made of any of an Al substrate, a Cu substrate, astainless substrate, and so forth. The thickness of the metal substrate2′ can be suitably set taking into account the size of the microreactor1′, properties such as a heat capacity and a thermal conductivity ofmetal to be used, the size of the microchannel portion 3 to be formed,and so forth. For example, it can be set within a range of about 50 to2000 μm.

The insulating film 4′ formed on the surface 2′b of the metal substrate2′ can be formed of, for example, polyimide, ceramic (Al₂O₃, SiO₂), orthe like. The thickness of such an insulating film 4′ can be suitablyset taking into account properties of a material to be used and soforth. For example, it can be set within a range of about 1 to 30 μm.

The microreactor 1, 1′ of the present invention as described above usesthe metal substrate 2, 2′ having a higher thermal conductivity and asmaller heat capacity as compared with a silicon substrate or a ceramicsubstrate, and therefore, heat is transmitted from the heater 5 to theapplied catalyst C with a high efficiency, so that there is enabled areformer for hydrogen production wherein the rising is fast uponstarting up from the stopped state and the utilization efficiency of theinput power to the heater is high.

Third Embodiment of Microreactor

FIG. 5 is a perspective view showing one embodiment of the microreactorof the present invention, FIG. 6 is an enlarged longitudinal sectionalview of the microreactor shown in FIG. 5, taken along line II-II, andFIG. 7 is an enlarged longitudinal sectional view of the microreactorshown in FIG. 5, taken along line III-III.

In FIGS. 5 to 7, the microreactor 11 of the present invention has atwo-step structure in which a metal substrate 12 and a metal substrate22 are joined together. The first-step metal substrate 12 comprises amicrochannel portion 13 formed on one surface 12 a thereof, a throughhole 19 having an opening at a predetermined portion of the microchannelportion 13, an insulating film 14 in the form of a metal oxide filmformed on the inside of the through hole 19, on the inside of themicrochannel portion 13, and on the other surface 12 b and side surfaces12 c of the metal substrate 12, a heater 15 provided on the surface 12 bof the metal substrate 12 via the insulating film 14, and a catalyst C1supported on the microchannel portion 13. Further, the heater 15 isformed with electrodes 16 and 16, and a heater protective layer 17having electrode opening portions 17 a and 17 a for exposing theelectrodes 16 and 16 and an opening portion 17 b for exposing theopening of the foregoing through hole 19 is provided so as to cover theheater 15.

On the other hand, the second-step metal substrate 22 comprises amicrochannel portion 23 formed on one surface 22 a thereof, a throughhole 29. having an opening at a predetermined portion of themicrochannel portion 23, an insulating film 24 in the form of a metaloxide film formed on the inside of the through hole 29, on the inside ofthe microchannel portion 23, and on side surfaces 22 c of the metalsubstrate 22, a catalyst C2 supported on the microchannel portion 23,and a cover member 28 joined to the surface 22 a so as to cover themicrochannel portion 23. The cover member 28 is provided with a gasoutlet 28 a.

FIG. 8 is a perspective view showing the state where the heaterprotective layer 17 is peeled off in the microreactor 11 shown in FIG.5. As shown in FIG. 8, the heater 15 is provided on the surface 12 b ofthe metal substrate 12 via the insulating layer 14. The opening portion17 b of the heater protective layer 17 serves as a feed material inlet.Incidentally, the heater 15 may be provided so as to further surroundthe through hole 19.

FIG. 9 is a perspective view showing the side, where the microchannelportion 13 is formed, of the first-step metal substrate 12 forming themicroreactor 11 shown in FIG. 5. As shown in FIG. 9, the microchannelportion 13 is formed so as to leave comb-shaped ribs 12A and 12B and hasa shape that is continuous from an end portion 13 a to an end portion 13b. The opening of the through hole 19 is exposed at the end portion 13 aof the microchannel portion 13.

FIG. 10 is a perspective view showing the side, where the microchannelportion 23 is formed, of the second-step metal substrate 22 forming themicroreactor 11 shown in FIG. 5. As shown in FIG. 10, the microchannelportion 23 is formed so as to leave comb-shaped ribs 22A and 22B and hasa shape that is continuous from an end portion 23 a to an end portion 23b. The opening of the through hole 29 is exposed at the end portion 23 aof the microchannel portion 23, and the other opening of the throughhole 29 is located at the end portion 13 b of the microchannel portion13 of the foregoing metal substrate 12 in the two-step stackedstructure. Further, in the microreactor 11, the gas outlet 28 a of thecover member 28 is located at the end portion 23 b of the microchannelportion 23. Thereby, as shown by arrows a in FIG. 7, there is formed acontinuous flow path running from the opening portion 17 b, serving asthe feed material inlet, of the heater protective layer 17, through thethrough hole 19 of the first-step metal substrate 12, and in themicrochannel portion 13 from the end portion 13 a, then running from theend portion 13 b, through the through hole 29 of the second-step metalsubstrate 22, and in the microchannel portion 23 from the end portion 23a, then passing through the gas outlet 28 a from the end portion 23 b toreach the outside.

For the metal substrate 12, 22 forming the microreactor 11 of thepresent invention, there can be used such metal that can form the metaloxide film (insulating film 14, 24) by anodic oxidation. As such metal,there can be cited, for example, Al, Si, Ta, Nb, V, Bi, Y, W, Mo, Zr,Hf, or the like. Among these metals, particularly Al is preferably usedin terms of processing suitability, properties such as a heat capacityand a thermal conductivity, and a unit price. The thickness of the metalsubstrate 12, 22 can be suitably set taking into account the size of themicroreactor 11, properties such as a heat capacity and a thermalconductivity of metal to be used, the size of the microchannel portion13, 23 to be formed, and so forth. For example, it can be set within arange of about 50 to 2000 μm.

The formation of the metal oxide film (insulating film 14, 24) by anodicoxidation on the metal substrate 12, 22 can be implemented by, in thestate where the metal substrate 12, 22 is connected to an anode as anexternal electrode, immersing the metal substrate 12, 22 in an anodeoxidizing solution so as to confront a cathode and energizing it. Thethickness of the metal oxide film (insulating film 14, 24) can be setwithin a range of, for example, about 5 to 150 μm.

The microchannel portion 13, 23 formed on the metal substrate 12, 22 isnot limited to the shape as shown in FIG. 9 or FIG. 10, but can beformed into a desirable shape like one wherein an amount of the catalystC1, C2 supported on the microchannel portion 13, 23 increases and theflow path length in which a feed material contacts with the catalyst C1,C2 is prolonged. Normally, the depth of the microchannel portion 13, 23can be set within a range of about 50 to 1000 μm, the width thereof canbe set within a range of about 50 to 1000 μm, and the flow path lengththereof can fall within a range of about 30 to 400 mm.

In the present invention, since the insulating film 14, 24 in the formof the metal oxide film is formed also on the inside of the microchannelportion 13, 23, a applying amount of the catalyst C1, C2 is increased toenable stable catalyst applying due to a surface structure of the metaloxide film having microholes.

As the catalysts C1 and C2, it is possible to use known catalysts thathave conventionally been employed for steam reforming. For example, whenmixing of feed materials, vaporization of the mixed feed material, andreforming of mixture gas are carried out in the microchannel portion 13of the first-step metal substrate 12 and removal of impurities fromreformed gas is carried out in the microchannel portion 23 of thesecond-step metal substrate 22, it is possible to use Cu—ZnO/Al₂O₃ orthe like as the catalyst C1, and Pt/Al₂O₃ or the like as the catalystC2.

The heater 15 forming the microreactor 11 of the present invention isfor supplying heat required for steam heating of the feed material,which is an endothermic reaction, and it is possible to use therefor amaterial such as carbon paste, nichrome (Ni—Cr alloy), W (tungsten), orMo (molybdenum). The heater 15 can have a shape that is obtained by, forexample, drawing around a fine line having a width of about 10 to 200 μmover the whole of a region on the metal substrate surface 12 b(insulating film 14) corresponding to a region where the microchannelportion 13 is formed, but not closing the through hole 19.

Incidentally, when the heater is provided on only one metal substratelike in this embodiment, it is preferable to provide it on the metalsubstrate that carries out reforming of the mixture gas.

Such a heater 15 is formed with the electrodes 16 and 16 forenergization. The electrodes 16 and 16 for energization can be formedusing a conductive material such as Au, Ag, Pd, or Pd—Ag.

The heater protective layer 17 has the electrode opening portions 17 aand 17 b for exposing the foregoing electrodes 16 and 16 and the openingportion 17 b for exposing the opening of the foregoing through hole 19,and is disposed so as to cover the heater 15. The heater protectivelayer 17 can be formed of, for example, photosensitive polyimide,polyimide varnish, or the like. The thickness of the heater protectivelayer 17 can be suitably set taking into account a material to be usedand so forth. For example, it can be set within a range of about 2 to 25μm.

For the cover member 28 forming the microreactor 11 of the presentinvention, an Al alloy, a Cu alloy, a stainless material, or the likecan be used. The thickness of the cover member 28 can be suitably settaking into account a material to be used and so forth. For example, itcan be set within a range of about 20 to 400 μm. The gas outlet 28 a ofthe cover member 28 is provided so as to be located at the end portion23 b of the flow path of the microchannel portion 23 formed on the metalsubstrate 22.

Fourth Embodiment of Microreactor

FIG. 11 is a longitudinal sectional view, corresponding to FIG. 6,showing another embodiment of the microreactor of the present invention.In FIG. 11, the microreactor 11′ of the present invention has a two-stepstructure in which a metal substrate 12′ and a metal substrate 22′ arejoined together. The first-step metal substrate 12′ comprises amicrochannel portion 13 formed on one surface 12′a thereof, a throughhole 19 (not illustrated) having an opening at a predetermined portionof the microchannel portion 13, an insulating film 14′ formed on theother surface 12′b of the metal substrate 12′, a heater 15 provided onthe surface 12′b of the metal substrate 12′ via the insulating film 14′,and a catalyst C1 supported on the microchannel portion 13. Further, theheater 15 is formed with electrodes 16 and 16, and a heater protectivelayer 17 having electrode opening portions 17 a and 17 a for exposingthe electrodes 16 and 16 and an opening portion 17 b (not illustrated)for exposing the opening of the foregoing through hole 19 is provided soas to cover the heater 15.

On the other hand, the second-step metal substrate 22′ comprises amicrochannel portion 23 formed on one surface 22′a thereof, a throughhole 29 (not illustrated) having an opening at a predetermined portionof the microchannel portion 23, a catalyst C2 supported on themicrochannel portion 23, and a cover member 28 joined to the surface22′a so as to cover the microchannel portion 23. The cover member 28 isprovided with a gas outlet 28 a.

Such a microreactor 11′ is the same as the foregoing microreactor 11except that the metal member 12′, 22′ and the insulating layer 14′, 24′are different and that the metal oxide film (insulating layer 14, 24) isnot formed in the microchannel portion 13, 23 or the through hole 19,29, and therefore, the same constituent members are assigned the samemember numerals to omit description thereof.

As the metal substrate 12′, 22′ forming the microreactor 11′ of thepresent invention, use can be made of any of an Al substrate, a Cusubstrate, a stainless substrate, and so forth. The thickness of themetal substrate 12′, 22′ can be suitably set taking into account thesize of the microreactor 11′, properties such as a heat capacity and athermal conductivity of metal to be used, the size of the microchannelportion 13 to be formed, and so forth. For example, it can be set withina range of about 50 to 2000 μm.

The insulating film 14′ formed on the surface 12′b of the metalsubstrate 12′ can be formed of, for example, polyimide, ceramic (Al₂O₃,SiO₂), or the like. The thickness of such an insulating film 14′ can besuitably set taking into account properties of a material to be used andso forth. For example, it can be set within a range of about 1 to 30 μm.

In the microreactor 11, 11′ of the present invention as described above,a series of the operations, i.e. mixing of the feed materials,vaporization thereof, reforming of the mixture gas, and removal of theimpurities, can be performed in the microchannel portions 13 and 23,carrying the catalysts, of the metal substrates 12 and 22, 12′ and 22′stacked in two steps, so that high purity hydrogen gas can be obtainedfrom the gas outlet 28 a of the cover member 28. Therefore, the spaceefficiency is largely improved as compared with a case where a pluralityof microreactors are connected by connecting pipes. Further, use is madeof the metal substrates 12, 12′, 22, 22′ having a higher thermalconductivity and a smaller heat capacity as compared with a siliconsubstrate or a ceramic substrate, and therefore, heat is transmittedfrom the heater 15 to the applied catalysts C1 and C2 with a highefficiency, so that there is enabled a reformer for hydrogen productionwherein the rising is fast upon starting up from the stopped state andthe utilization efficiency of the input power to the heater is high.

The foregoing embodiments of the microreactors are only examples. Forexample, a multi-step structure with three or more steps may be employedand, in this case, it is preferable to provide the heater at least onthe metal substrate that carries out reforming of the mixture gas.

Fifth Embodiment of Microreactor

FIG. 12 is a perspective view showing one embodiment of the microreactorof the present invention, and FIG. 13 is an enlarged longitudinalsectional view of the microreactor shown in FIG. 12, taken along lineA-A. In FIGS. 12 and 13, the microreactor 101 of the present inventionhas a joined body 115 comprising a metal substrate 102 formed with amicrochannel portion 103 on one surface 102 a thereof, and a metal covermember 104 joined to the surface 102 a of the metal substrate 102 so asto cover the microchannel portion 103. Inside the joined body 115, thereis formed a flow path 105 composed of the microchannel portion 103 andthe metal cover member 104, and a catalyst C is supported on the wholeinner wall surface of the flow path 105 via a metal oxide film 106.Further, the foregoing metal cover member 104 is provided with a feedmaterial inlet 104 a and a gas outlet 104 b which are located atrespective end portions of the flow path 105. The foregoing metal oxidefilm 106 is an insulating film and is also formed on the surfaces of thejoined body 115 (a surface 102 b and side surfaces 102 c of the metalsubstrate 102 and the surface of the metal cover member 104) apart fromthe inner wall surface of the flow path 105. Further, a heater 107 isprovided on the surface 102 b of the metal substrate 102 via the metaloxide film 106 and formed with electrodes 108 and 108, and a heaterprotective layer 109 having electrode opening portions 109 a and 109 afor exposing the electrodes 108 and 108 is provided so as to cover theheater 107.

FIG. 14 is a perspective view showing the side, where the microchannelportion 103 is formed, of the metal substrate 102 of the microreactor101 shown in FIG. 12. As shown in FIG. 14, the microchannel portion 103is formed so as to turn back by 180 degrees at respective tip portionsof comb-shaped ribs 102A and 102B and has a shape that is continuousfrom an end portion 103 a to an end portion 103 b while meandering. Theshape of an inner wall surface of the microchannel portion 103 in asection perpendicular to a fluid flow direction of the flow path 105 isgenerally semicircular. Further, the turnback of the flow path at eachof the tip portions of the comb-shaped ribs 102A and 102B is roundedwith no angular portion. The feed material inlet 104 a of the metalcover member 104 is located at the end portion 103 a of the microchannelportion 103, and the gas outlet 104 b is located at the end portion 103b of the microchannel portion 103.

For the metal substrate 102 forming the microreactor 101, there can beused such metal that can form the metal oxide film (insulating film) 106by anodic oxidation. As such metal, there can be cited, for example, Al,Si, Ta, Nb, V, Bi, Y, W, Mo, Zr, Hf, or the like. Among these metals,particularly Al is preferably used in terms of processing suitability,properties such as a heat capacity and a thermal conductivity, and aunit price. The thickness of the metal substrate 102 can be suitably settaking into account the size of the microreactor 101, properties such asa heat capacity and a thermal conductivity of metal to be used, the sizeof the microchannel portion 103 to be formed, and so forth. For example,it can be set within a range of about 50 to 2000 μm.

The microchannel portion 103 formed on the metal substrate 102 is notlimited to the shape as shown in FIG. 14, but can be formed into adesirable shape like one wherein an amount of the catalyst C supportedon the microchannel portion 103 increases and the flow path length inwhich a feed material contacts with the catalyst C is prolonged.Particularly, such a shape of the microchannel portion 103 is preferablewherein an angular portion (e.g. a portion of the internal wall surfacethat is angularly bent at a position where the direction of the flowpath changes) does not exist on the internal wall surface along thefluid flow direction of the flow path 105. Further, the shape of theinner wall surface of the microchannel portion 103 in the sectionperpendicular to the fluid flow direction of the flow path 105 ispreferably a circular arc shape, a semicircular shape, or a U-shape. Forexample, the depth of such a microchannel portion 103 can be set withina range of about 100 to 1000 μm, the width thereof can be set within arange of about 100 to 1000 μm, and the flow path length thereof can fallwithin a range of about 30 to 300 mm.

In this embodiment, since the metal oxide film 106 is formed on theinner wall surface of the flow path 105, a applying amount of thecatalyst C is increased to enable stable catalyst applying due to asurface structure of the metal oxide film having microholes.

As the catalyst C, it is possible to use a known catalyst that hasconventionally been employed for steam reforming.

For the metal cover member 104 forming the microreactor 101, there canbe used such metal that can form the metal oxide film (insulating film)106 by anodic oxidation. As such metal, there can be cited, for example,Al, Si, Ta, Nb, V, Bi, Y, W, Mo, Zr, Hf, or the like. Among thesemetals, particularly Al is preferably used in terms of processingsuitability, properties such as a heat capacity and a thermalconductivity, and a unit price. The thickness of the metal cover member104 can be suitably set taking into account a material to be used and soforth. For example, it can be set within a range of about 20 to 200 μm.The feed material inlet 104 a and the gas outlet 104 b of the metalcover member 104 are provided so as to be located at both end portions103 a and 103 b of the microchannel portion 103 formed on the metalsubstrate 102.

The formation of the metal oxide film (insulating film) 106 by anodicoxidation on the joined body 115 formed by joining together the metalsubstrate 102 and the metal cover member 104 can be implemented by, inthe state where the joined body 115 is connected to an anode as anexternal electrode, immersing the joined body 115 in an anode oxidizingsolution so as to confront a cathode and energizing it. The thickness ofthe metal oxide film (insulating film) 106 can be set within a range of,for example, about 5 to 150 μm.

The heater 107 forming the microreactor 101 is for supplying heatrequired for steam heating of the feed material, which is an endothermicreaction, and it is possible to use therefor a material such as carbonpaste, nichrome (Ni—Cr alloy), W (tungsten), or Mo (molybdenum). Theheater 107 can have a shape like one that is obtained by, for example,drawing around a fine line having a width of about 10 to 200 μm over thewhole of a region on the metal substrate surface 102 b (metal oxide film106) corresponding to a region where the microchannel portion 103 isformed.

Such a heater 107 is formed with the electrodes 108 and 108 forenergization. The electrodes 108 and 108 for energization can be formedusing a conductive material such as Au, Ag, Pd, or Pd—Ag.

The heater protective layer 109 has the electrode opening portions 109 aand 109 a for exposing the foregoing electrodes 108 and 108 and isdisposed so as to cover the heater 107. The heater protective layer 109can be formed of, for example, photosensitive polyimide, polyimidevarnish, or the like. The thickness of the heater protective layer 109can be suitably set taking into account a material to be used and soforth. For example, it can be set within a range of about 2 to 25 μm.

Sixth Embodiment of Microreactor

FIG. 15 is a longitudinal sectional view, corresponding to FIG. 13,showing another embodiment of the microreactor of the present invention.In FIG. 15, the microreactor 121 of the present invention has a joinedbody 135 comprising a metal substrate 122 formed with a microchannelportion 123 on one surface 122 a thereof, and a metal cover member 124joined to the surface 122 a of the metal substrate 122 so as to coverthe microchannel portion 123. Inside the joined body 135, there isformed a flow path 125 composed of the microchannel portion 123 and themetal cover member 124, and a catalyst C is supported on the whole innerwall surface of the flow path 125 via a metal oxide film 126. Theforegoing metal cover member 124 is provided with a feed material inlet124 a and a gas outlet 124 b which are located at respective endportions of the flow path 125. Further, an insulating film 130 is formedon the surface of the joined body 135 (a surface 122 b of the metalsubstrate 122), and a heater 127 is provided on the insulating film 130.The heater 127 is formed with electrodes 128 and 128, and a heaterprotective layer 129 having electrode opening portions 129 a and 129 afor exposing the electrodes 128 and 128 is provided so as to cover theheater 127.

For the metal substrate 122 forming such a microreactor 121, it ispossible to use a material that can form a metal oxide film through aboehmite treatment of Cu, stainless, Fe, Al, or the like. The thicknessof the metal substrate 122 can be suitably set taking into account thesize of the microreactor 121, properties such as a heat capacity and athermal conductivity of metal to be used, the size of the microchannelportion 123 to be formed, and so forth. For example, it can be setwithin a range of about 50 to 2000 μm.

The microchannel portion 123 of the metal substrate 122 can be the sameas the microchannel portion 103 of the foregoing embodiment.

For the metal cover member 124 forming the microreactor 121, it ispossible to use a material that can form a metal oxide film through aboehmite treatment of Cu, stainless, Fe, Al, or the like. The thicknessof the metal cover member 124 can be suitably set taking into account amaterial to be used and so forth. For example, it can be set within arange of about 20 to 200 μm. The feed material inlet 124 a and the gasoutlet 124 b of the metal cover member 124 are provided so as to belocated at both end portions of the microchannel portion 123 formed onthe metal substrate 122.

The formation of the metal oxide film 126 by the boehmite treatment inthe flow path 125 of the joined body 135 formed by joining together themetal substrate 122 and the metal cover member 124 can be implementedby, for example, using a suspension with boehmite alumina such asalumina sol being dispersed therein, and pouring the suspension with afully lowered viscosity into the flow path 125, thereafter, drying it tofix a boehmite coating on the inner surface of the flow path (washcoatprocess). The metal oxide film 126 formed by such a boehmite treatmentis an aluminum oxide thin film, and the thickness thereof can be setwithin a range of, for example, about 0.5 to 5.0 μm.

The insulating film 130 formed on the surface 122 b of the metalsubstrate 122 can be formed of, for example, polyimide, ceramic (Al₂O₃,SiO₂), or the like. The thickness of such an insulating film 130 can besuitably set taking into account properties of a material to be used andso forth. For example, it can be set within a range of about 1 to 30 μm.

The catalyst C, the heater 127, the electrodes 128 and 128, and theheater protective layer 129 forming the microreactor 121 can be the sameas the catalyst C, the heater 107, the electrodes 108 and 108, and theheater protective layer 109 forming the microreactor 101, respectively,and therefore, description thereof is omitted herein.

In the microreactor 101, 121 of the present invention as describedabove, since the catalyst C is supported on the whole inner wall surfaceof the flow path 105, 125, the reaction area is increased to therebyobtain a high reaction efficiency. Further, use is made of the metalsubstrate 102, 122 and the metal cover member 104, 124 each having ahigher thermal conductivity and a smaller heat capacity as compared witha silicon substrate or a ceramic substrate, and therefore, heat istransmitted from the heater 107, 127 to the supported catalyst C with ahigh efficiency, so that there is enabled a reformer for hydrogenproduction wherein the rising is fast upon starting up from the stoppedstate and the utilization efficiency of the input power to the heater ishigh.

Seventh Embodiment of Microreactor

FIG. 16 is a perspective view showing another embodiment of themicroreactor of the present invention, and FIG. 17 is an enlargedlongitudinal sectional view of the microreactor shown in FIG. 16, takenalong line B-B. In FIGS. 16 and 17, the microreactor 141 of the presentinvention has a joined body 155 in which a metal substrate 142 formedwith a microchannel portion 143 on one surface 142 a thereof, and ametal substrate 144 formed with a microchannel portion 145 on onesurface 144 a thereof are joined together such that the microchannelportion 143 and the microchannel portion 145 confront each other. Insidethe joined body 155, there is formed a flow path 146 composed of theconfronting microchannel portions 143 and 145, and a catalyst C issupported on the whole inner wall surface of the flow path 146 via ametal oxide film 147. Further, both end portions of the flow path 146are exposed at one end surface of the foregoing joined body 155 to forma feed material inlet 146 a and a gas outlet 146 b, respectively. Theforegoing metal oxide film 147 is an insulating film and is also formedon the surfaces of the joined body 155 (a surface 142 b and sidesurfaces 142 c of the metal substrate 142, and a surface 144 b and sidesurfaces 144 c of the metal substrate 144) apart from the inner wallsurface of the flow path 146. Further, a heater 148 is provided on thesurface 142 b of the metal substrate 142 via the metal oxide film 147and formed with electrodes 149 and 149, and a heater protective layer150 having electrode opening portions 150 a and 150 a for exposing theelectrodes 149 and 149 is provided so as to cover the heater 148.

FIG. 18 is a perspective view showing the side, where the microchannelportion 143 is formed, of the metal substrate 142 and the side, wherethe microchannel portion 145 is formed, of the metal substrate 144, ofthe microreactor 141 shown in FIG. 16. As shown in FIG. 18, themicrochannel portion 143 is formed so as to turn back by 180 degrees atrespective tip portions of comb-shaped ribs 142A and 142B and has ashape that is continuous from an end portion 143 a to an end portion 143b while meandering. The microchannel portion 145 is formed so as to turnback by 180 degrees at respective tip portions of comb-shaped ribs 144Aand 144B and has a shape that is continuous from an end portion 145 a toan end portion 145 b while meandering. Further, the microchannel portion143 and the microchannel portion 145 have pattern shapes that are in asymmetrical relationship. with respect to a joining plane between themetal substrates 142 and 144. Therefore, by joining together the metalsubstrates 142 and 144, the end portion 143 a of the microchannelportion 143 is located on the end portion 145 a of the microchannelportion 145, and the end portion 143 b of the microchannel portion 143is located on the end portion 145 b of the microchannel portion 145, sothat the microchannel portion 143 and the microchannel portion 145completely confront each other. The shape of the inner wall surface ofthe flow path 146 formed by such microchannel portions 143 and 145 isgenerally circular in a section perpendicular to a fluid flow directionof the flow path 146. Further, the turnback of the flow path 146 at eachof the tip portions of the comb-shaped ribs 142A and 142B or thecomb-shaped ribs 144A and 144B is rounded with no angular portion. Theend portion 143 a of the microchannel portion 143 and the end portion145 a of the microchannel portion 145 form the feed material inlet 146a, while the end portion 143 b of the microchannel portion 143 and theend portion 145 b of the microchannel portion 145 form the gas outlet146 b.

For the metal substrate 142, 144 forming the microreactor 141, there canbe used such metal that can form the metal oxide film (insulating film)147 by anodic oxidation. As such metal, it is possible to use the sameone for the metal substrate 102 in the foregoing embodiment. Further,the thickness of the metal substrate 142, 144 can be suitably set takinginto account the size of the microreactor 141, properties such as a heatcapacity and a thermal conductivity of metal to be used, the size of themicrochannel portion 143, 145 to be formed, and so forth. For example,it can be set within a range of about 400 to 1000 μm.

The microchannel portion 143, 145 formed on the metal substrate 142, 144is not limited to the shape as shown in FIG. 18, but can be formed intoa desirable shape like one wherein an amount of the catalyst C supportedon the microchannel portion 143, 145 increases and the flow path lengthin which a feed material contacts with the catalyst C is prolonged.Particularly, such a shape of the microchannel portion 143, 145 ispreferable wherein an angular portion (e.g. a portion of the internalwall surface that is angularly bent at a position where the direction ofthe flow path changes) does not exist on the internal wall surface alongthe fluid flow direction of the flow path 146. Further, the shape of theinner wall surface of the microchannel portion 143, 145 in the sectionperpendicular to the fluid flow direction is preferably a circular arcshape, a semicircular shape, or a U-shape. Thereby, the shape of theinner wall surface, in the section perpendicular to the fluid flowdirection, of the fluid path 146 formed by the microchannel portions 143and 145 becomes generally circular. For example, the depth of such amicrochannel portion 143, 145 can be set within a range of about 100 to1000 μm, the width thereof can be set within a range of about 100 to1000 μm, and the flow path length thereof can fall within a range ofabout 30 to 300 mm.

In this embodiment, since the metal oxide film 147 is formed on theinner wall surface of the flow path 146, a applying amount of thecatalyst C is increased to enable stable catalyst applying due to asurface structure of the metal oxide film having microholes.

As the catalyst C, it is possible to use a known catalyst that hasconventionally been employed for steam reforming.

The formation of the metal oxide film (insulating film) 147 by anodicoxidation on the joined body 155 formed by joining together the metalsubstrates 142 and 144 can be implemented by, in the state where thejoined body 155 is connected to an anode as an external electrode,immersing the joined body 155 in an anode oxidizing solution so as toconfront a cathode and energizing it. The thickness of the metal oxidefilm (insulating film) 147 can be set within a range of, for example,about 5 to 150 μm.

The catalyst C, the heater 148, the electrodes 149 and 149, and theheater protective layer 150 forming the microreactor 141 can be the sameas the catalyst C, the heater 107, the electrodes 108 and 108, and theheater protective layer 109 forming the microreactor 101, respectively,and therefore, description thereof is omitted herein.

Eighth Embodiment of Microreactor

FIG. 19 is a longitudinal sectional view, corresponding to FIG. 17,showing another embodiment of the microreactor of the present invention.In FIG. 19, the microreactor 161 of the present invention has a joinedbody 175 in which a metal substrate 162 formed with a microchannelportion 163 on one surface 162 a thereof, and a metal substrate 164formed with a microchannel portion 165 on one surface 164 a thereof arejoined together such that the microchannel portion 163 and themicrochannel portion 165 confront each other. Inside the joined body175, there is formed a flow path 166 composed of the confrontingmicrochannel portions 163 and 165, and a catalyst C is supported on thewhole inner wall surface of the flow path 166 via a metal oxide film167. Further, both end portions of the flow path 166 are exposed at oneend surface of the foregoing joined body 175 to form a feed materialinlet (not illustrated) and a gas outlet (not illustrated),respectively. Further, an insulating film 171 is formed on the surfaceof the joined body 175 (a surface 162 b of the metal substrate 162), anda heater 168 is provided on the insulating film 171. The heater 168 isformed with electrodes 169 and 169, and a heater protective layer 170having electrode opening portions 170 a and 170 a for exposing theelectrodes 169 and 169 is provided so as to cover the heater 168.

For the metal substrate 162, 164 forming such a microreactor 161, it ispossible to use a material that can form a metal oxide film through aboehmite treatment of Cu, stainless, Fe, Al, or the like. The thicknessof the metal substrate 162, 164 can be suitably set taking into accountthe size of the microreactor 161, properties such as a heat capacity anda thermal conductivity of metal to be used, the size of the microchannelportion 163, 165 to be formed, and so forth. For example, it can be setwithin a range of about 400 to 1000 μm.

The microchannel portion 163, 165 of the metal substrate 162, 164 can bethe same as the microchannel portion 143, 145 of the foregoing thirdembodiment.

The formation of the metal oxide film 167 by the boehmite treatment inthe flow path 166 of the joined body 175 formed by joining together themetal substrates 162 and 164 can be carried out according to theboehmite treatment for the joined body 135 in the foregoing secondembodiment. The metal oxide film 167 formed by the boehmite treatment isan aluminum oxide thin film, and the thickness thereof can be set withina range of, for example, about 0.5 to 5.0 μm.

The insulating film 171 formed on the surface 162 b of the metalsubstrate 162 can be the same as the insulating film 130 in theforegoing second embodiment.

Further, the catalyst C, the heater 168, the electrodes 169 and 169, andthe heater protective layer 170 forming the microreactor 161 can be thesame as the catalyst C, the heater 107, the electrodes 108 and 108, andthe heater protective layer 109 forming the microreactor 101 in theforegoing first embodiment, respectively, and therefore, descriptionthereof is omitted herein.

In the microreactor 141, 161 of the present invention as describedabove, since the catalyst C is supported on the whole inner wall surfaceof the flow path 146, 166, the reaction area is increased to therebyobtain a high reaction efficiency. Further, use is made of the metalsubstrates 142 and 144, 162 and 164 each having a higher thermalconductivity and a smaller heat capacity as compared with a siliconsubstrate or a ceramic substrate, and therefore, heat is transmittedfrom the heater 148, 168 to the supported catalyst C with a highefficiency, so that there is enabled a reformer for hydrogen productionwherein the rising is fast upon starting up from the stopped state andthe utilization efficiency of the input power to the heater is high.

The foregoing embodiments of the microreactors are only examples. Forexample, the positions of the feed material inlet and the gas outlet canbe set to desirable positions by changing the shapes of the microchannelportions.

Ninth Embodiment of Microreactor

FIG. 20 is a perspective view showing one embodiment of the microreactorof the present invention, FIG. 21 is an enlarged longitudinal sectionalview of the microreactor shown in FIG. 20, taken along line I-I, andFIG. 22 is a perspective view showing the state where constituentmembers of the microreactor shown in FIG. 20 are separated from eachother. In FIGS. 20 to 22, the microreactor 201 of the present inventionis configured such that three unit flow path members 202 a, 202 b, and202 c are coupled and retained together in a multi-step state with threesteps by a coupling member 204 and a fixing member 206. Gaps 207 areprovided between the respective unit flow path members 202 a, 202 b, and202 c.

The unit flow path members 202 a, 202 b, and 202 c each have a flow pathinside, and this flow path has one end portion forming an inlet and theother end portion forming an outlet. Among the three unit flow pathmembers 202 a, 202 b, and 202 c, the unit flow path members 202 b and202 c are unit microreactors each carrying a catalyst in the flow path.Specifically, as shown in FIG. 21, each of the unit flow path members202 a, 202 b, and 202 c has a joined body 210 in which a metal substrate211 formed with a microchannel portion 212 and a metal substrate 213formed with a microchannel portion 214 are joined together such that themicrochannel portion 212 and the microchannel portion 214 confront eachother, and a metal oxide film (insulating layer) 216 is formedtherearound. Inside the joined body 210, there is formed a flow path 215composed of the confronting microchannel portions 212 and 214. Further,in the unit flow path members (unit microreactors) 202 b and 202 c,catalysts C1 and C2 are respectively supported on the whole inner wallsurfaces of the flow paths 215 via the metal oxide films 216.Incidentally, in the illustrated example, the unit flow path member 202a carrying no catalyst on the inner wall surface of the flow path 215also has the metal oxide film 216 on the inner wall surface of the flowpath 215 within the joined body. 210, but it may also be configured notto have this metal oxide film 216.

As shown in FIG. 22, the foregoing joined body 210 forming each of theunit flow path members 202 a, 202 b, and 202 c has a pair of projectingportions 210 a and 210 b in the same direction. FIG. 23 is a perspectiveview for describing the state of the flow path 215 using the unit flowpath member 202 a as an example. As shown in FIG. 23, the flow path 215has a shape continuously meandering from an end portion located at theprojecting portion 210 a to an end portion located at the projectingportion 210 b. The end portion of the flow path 215 located at theprojecting portion 210 a forms an inlet 203 a, while the end portion ofthe flow path 215 located at the projecting portion 210 b forms anoutlet 203 b. Specifically, in each of the unit flow path member 202 aand the unit flow path member (unit microreactor) 202 c, the end portionof the flow path 215 located at the projecting portion 210 a forms theinlet 203 a, while the end portion of the flow path 215 located at theprojecting portion 210 b forms the outlet 203 b. On the other hand, inthe unit flow path member (unit microreactor) 202 b, the end portion ofthe flow path 215 located at the projecting portion 210 a forms theoutlet 203 b, while the end portion of the flow path 215 located at theprojecting portion 210 b forms the inlet 203 a. Therefore, from thefirst-step unit flow path member toward the third-step unit flow pathmember (unit microreactor), the inlet 203 a, the outlet 203 b, and theinlet 203 a are arrayed in the order named on the side of the projectingportions 210 a, while the outlet 203 b, the inlet 203 a, and the outlet203 b are arrayed in the order named on the side of the projectingportions 210 b.

Further, a heater 217 is provided on one surface of the joined body 210forming each of the unit flow path members 202 a, 202 b, and 202 c. Theheater 217 is formed with electrodes 218 and 218, and a heaterprotective layer 219 is provided so as to expose portions of theelectrodes 218 and 218 and to cover the heater 217. FIG. 22 shows thestate where the heater protective layer 219 of the unit flow path member202 a is separated. Incidentally, although the unit flow path member 202a not being the unit microreactor is also provided with the heater 217and the electrodes 218 and 218 in the illustrated example, it may alsobe configured that only the unit flow path members being the unitmicroreactors are each provided with the heater 217 and the electrodes218 and 218.

The coupling member 204 is for retaining the respective unit flow pathmembers 202 a, 202 b, and 202 c in the multi-step state and has astructure body 221 of a shape in which block bodies 221 a and 221 bsandwich a block body 221 c therebetween. FIG. 24 is a diagram showingthe side, where coupling portions are formed, of the coupling member204, and FIG. 25 is a sectional view of the coupling member shown inFIG. 24, wherein FIG. 25A is a sectional view taken along line II-II andFIG. 25B is a sectional view taken along line III-III. As shown in FIGS.24 and 25, on one side of the block bodies 221 a and 221 b, there areprovided a plurality of coupling portions 222 for tightly retaining therespective unit flow path members 202 a, 202 b, and 202 c at theprojecting portions 210 a and 210 b of the joined bodies 210 where theinlets 203 a and the outlets 203 b are located. Further, a feed materialinlet 223 is provided on the other side of the block body 221 a, while agas outlet 224 is provided on the other side of the block body 221 b.

The coupling portions 222 provided in the block body 221 a comprise anintroduction coupling portion 222 a connected to the feed material inlet223 via an internal flow path 226, and a pair of step shift couplingportions 222 d and 222 e connected to each other via an internalcommunication path 225 a, which are arrayed in a row. On the other hand,the coupling portions 222 provided in the block body 221 b comprise apair of step shift coupling portions 222 b and 222 c connected to eachother via an internal communication path 225 b, and a discharge couplingportion 222 f connected to the gas outlet 224 via an internal flow path227, which are arrayed in a row. Further, in each of the couplingportions 222 (222 a, 222 b, 222 c, 222 d, 222 e, 222 f), a packing 228is disposed for tightly retaining in a gastight and liquidtight statethe projecting portion 210 a, 210 b of the joined body 210 forming eachof the unit flow path members 202 a, 202 b, and 202 c. The dimensions ofeach coupling portion 222 are suitably set corresponding to the shape ofthe projecting portion 210 a, 210 b of the unit flow path member to becoupled and retained.

In the foregoing coupling member 204, the projecting portion 210 a andthe projecting portion 210 b of the first-step unit flow path member 202a are inserted into the introduction coupling portion 222 a and the stepshift coupling portion 222 b, respectively, so as to be tightlyretained, the projecting portion 210 b and the projecting portion 210 aof the second-step unit flow path member (unit microreactor) 202 b areinserted into the step shift coupling portions 222 c and 222 d,respectively, so as to be tightly retained, and the projecting portion210 a and the projecting portion 210 b of the third-step unit flow pathmember (unit microreactor) 202 c are inserted into the step shiftcoupling portion 222 e and the discharge coupling portion 222 f,respectively, so as to be tightly retained. The foregoing packing 228 isfor making more reliable the tight retention of each unit flow pathmember 202 a, 202 b, 202 c by the coupling member 204, and may be, forexample, an O-ring or made of a material having elasticity such assilicon rubber. For making more reliable the tight retention of the unitflow path members 202 a, 202 b, and 202 c by the coupling member 204,auxiliary members of silicon rubber or the like having elasticity mayalso be provided around the projecting portions 210 a and the projectingportions 210 b, respectively.

The fixing member 206 is for fixing the other end portions of the unitflow path members 202 a, 202 b, and 202 c retained in the multi-stepstate by the foregoing coupling member 204, and comprises a frame body231 and partition members 232 a and 232 b for partitioning the inside ofthe frame body 231 into three steps. By disposing the end portions ofthe respective unit flow path members 202 a, 202 b, and 202 c so as tobe inserted in accommodating spaces 233 a, 233 b, and 233 c defined bythe partition members 232 a and 232 b, the fixing member 206 can fixedlyretain them in the multi-step state.

In the foregoing microreactor 201, feed materials introduced from thefeed material inlet 223 of the coupling member 204 pass through theinternal flow path 226 and reach the inlet 203 a of the first-step unitflow path member 202 a from the introduction coupling portion 222 a.Then, desired mixing of the feed materials is carried out in the flowpath 215 of the unit flow path member 202 a, and then, via the outlet203 b, the step shift coupling portion 222 b, the internal communicationpath 225 b, and the step shift coupling portion 222 c, the mixturereaches the inlet 203 a of the second-step unit flow path member (unitmicroreactor) 202 b. Then, after passing through the inside of the flowpath 215, where the catalyst C1 is applied, of the unit microreactor 202b, it is sent, via the outlet 203 b, the step shift coupling portion 222d, and the internal communication path 225 a, to the step shift couplingportion 222 e and reaches the inlet 203 a of the third-step unit flowpath member (unit microreactor) 202 c. Then, after passing through theinside of the fluid path 215, where the catalyst C2 is applied, of theunit microreactor 202 c, it passes through the outlet 203 b, thedischarge coupling portion 222 f, and the internal flow path 227 toreach the gas outlet 224.

In the foregoing microreactor 201, the heaters 217 are respectivelyarranged in the unit flow path members 202 a, 202 b, and 202 c, and thegaps 207 exist between the respective unit flow path members, andtherefore, unnecessary heat conduction between the respective unit flowpath members is prevented to thereby enable optimum temperature settingin the unit microreactors 202 b and 202 c, respectively.

Further, in the present invention, as shown in FIG. 26, for example, itmay also be configured such that a unit microreactor having a heater 217is only a second-step unit flow path member (unit microreactor) 202 b,and a first-step unit flow path member 202 a′ and a third-step unit flowpath member (unit microreactor) 202 c′ are not provided with the heater217. Then, a gap 207 for thermal insulation may be provided between thefirst-step unit flow path member 202 a′ and the second-step unit flowpath member (unit microreactor) 202 b, and a heat insulating material208 may be interposed between the second-step unit flow path member(unit microreactor) 202 b and the third-step unit flow path member (unitmicroreactor) 202 c′. As the heat insulating material 208, it ispossible to use, for example, glass wool, a ceramic substrate, or thelike.

Further, the positional relationship between the feed material inlet 223and the gas outlet 224 of the coupling member 204 is not limited to theillustrated example. For example, the feed material inlet 223 and thegas outlet 224 may be disposed at the same level by forming the internalflow path 227 in a bent fashion.

The foregoing microreactor 201 has the three-step structure wherein twoof the three unit flow path members are the unit microreactors. In thepresent invention, however, the number of unit flow path members may betwo or no less than four, and there is no particular limitation to thenumber of unit microreactors in unit flow path members. Then, dependingon the number of steps of the unit flow path members, the number of stepshift coupling portions of the coupling member 4 is set. Specifically,in the present invention, when n (n is an integer no less than two) unitflow path members exist, there can be provided (n−1) pairs of step shiftcoupling portions connected to each other by an internal communicationpath, among the coupling portions of the coupling member. With respectto the first-step unit flow path member, an inlet is coupled to andretained by an introduction coupling portion and an outlet is coupled toand retained by a step shift coupling portion. With respect to thesecond-step to (n−1)^(th)-step unit flow path members, an inlet iscoupled to and retained by a step shift coupling portion connected to aprior-step step shift coupling portion by an internal communication pathand an outlet is coupled to and retained by a step shift couplingportion of another pair. With respect to the n^(th)-step unit flow pathmember, an inlet is coupled to and retained by a step shift couplingportion connected to a prior-step step shift coupling portion by aninternal communication path and an outlet is coupled to and retained bya discharge coupling portion. Thereby, the microreactor of the presentinvention can be formed.

Here, description will be made of the respective members forming theforegoing microreactor 201.

First, the members forming the unit flow path member 202 a, 202 b, 202 cwill be described. For the metal substrate 211, 213 forming the joinedbody 210, there can be used such metal that can form the metal oxidefilm (insulating film) 216 by anodic oxidation. As such metal, there canbe cited, for example, Al, Si, Ta, Nb, V, Bi, Y, W, Mo, Zr, Hf, or thelike. Among these metals, particularly Al is preferably used in terms ofprocessing suitability, properties such as a heat capacity and a thermalconductivity, and a unit price. On the other hand, for the metalsubstrate 211, 213 forming the joined body 210, it is also possible touse a material that can form the metal oxide film 216 through a boehmitetreatment of Cu, stainless, Fe, Al, or the like. In this case, the metaloxide film 216 existing around the metal substrate 211, 213 may beformed likewise by the boehmite treatment, or polyimide, ceramic (Al₂O₃,SiO₂), or the like may be formed by the printing method such as screenprinting using a paste containing an insulating material, or the vacuumfilm forming method such as sputtering or vacuum deposition.

The thickness of the metal substrate 211, 213 can be suitably set takinginto account the size of the unit flow path member 202 a, 202 b, 202 c,properties such as a heat capacity and a thermal conductivity of metalto be used, the size of the microchannel portion 212, 214 to be formed,and so forth. For example, it can be set within a range of about 400 to1000 μm.

The microchannel portion 212, 214 formed on the metal substrate 211, 213is not limited to the illustrated shape, but can be formed into adesirable shape like one wherein an amount of the catalyst applied tothe microchannel portion 212, 214 increases and the flow path length inwhich a feed material contacts with the catalyst is prolonged. Forexample, the depth of the microchannel portion 212, 214 can be setwithin a range of about 100 to 1000 μm, the width thereof can be setwithin a range of about 100 to 1000 μm, and the flow path length thereofcan fall within a range of about 30 to 300 mm.

In this embodiment, since the metal oxide film 216 is formed on theinner wall surface of each flow path 215, an applying amount of thecatalyst C1, C2 is increased to enable stable catalyst applying due to asurface structure of the metal oxide film having microholes.

As the catalysts C1 and C2, it is possible to use known catalysts thathave conventionally been employed for hydrogen production. For example,when mixing of feed materials and vaporization thereof are carried outin the first-step unit flow path member 202 a, reforming of mixture gasis carried out in the second-step unit flow path member (unitmicroreactor) 202 b, and removal of impurities from reformed gas iscarried out in the third-step unit flow path member (unit microreactor)202 c, it is possible to use Cu—ZnO/Al₂O₃ or the like as the catalystC1, and Pt/Al₂O₃ or the like as the catalyst C2.

The heater 217 is for supplying heat required in each unit flow pathmember (unit microreactor), and it is possible to use therefor amaterial such as carbon paste, nichrome (Ni—Cr alloy), W (tungsten), orMo (molybdenum). The heater 217 can have a shape that is obtained by,for example, drawing around a fine line having a width of about 10 to200 μm over the whole of a region on the joined body 210 correspondingto a region where the microchannel portion is formed.

Such a heater 217 is formed with the electrodes 218 and 218 forenergization. The electrodes 218 and 218 for energization can be formedusing a conductive material such as Au, Ag, Pd, or Pd—Ag.

The heater protective layer 219 exposes portions of the foregoingelectrodes 218 and 218 and is disposed so as to cover the heater 217.The heater protective layer 219 can be formed of, for example,photosensitive polyimide, polyimide varnish, or the like. The thicknessof the heater protective layer 219 can be suitably set taking intoaccount a material to be used and so forth. For example, it can be setwithin a range of about 2 to 25 μm.

A material of the coupling member 204 may be stainless, Al, Fe, Cu, orthe like, and can be formed into a desired structure body shape usingmechanical processing and diffusion bonding, brazing or the like. Forexample, as shown in FIGS. 25A and 25B, the structure body 221 formingthe coupling member 4 can be composed of six members defined by fivechain lines L1 to L5. Then, grooves and through holes are formed inadvance on either surfaces of the six members for constituting thecoupling portions 222, the internal communication paths 225 a and 225 b,the internal flow paths 226 and 227, and the like. Then, the couplingmember 204 can be formed by diffusion bonding these six members in apredetermined order to unify them.

For the packing 228, it is possible to use an O-ring made of any ofvarious conventionally known materials, silicon rubber, or the like.

As a material of the fixing member 206, there can be cited the samematerial of the coupling member 204.

The foregoing embodiments of the microreactors are only examples, andthe present invention is not limited thereto.

For example, there is no particular limitation about the structures ofthe unit flow path members 202 a, 202 b, and 202 c as long as there is aflow path inside which is capable of carrying a catalyst, and this flowpath has one end portion forming an inlet and the other end portionforming an outlet. Therefore, as shown in FIG. 27A, a unit flow pathmember (unit microreactor) 202 b may have a joined body 241 comprising ametal substrate 242 formed with a microchannel portion 243 on onesurface thereof, a metal cover member 244 joined to the metal substrate242 so as to cover the microchannel portion 243, and a metal oxide film246 therearound. Inside the joined body 241, there is formed a flow path245 composed of the microchannel portion 243 and the metal cover member244, and a catalyst Cl is supported on the whole inner wall surface ofthe flow path 245 via the metal oxide film 246. On the other hand, asshown in FIG. 27B, a unit flow path member (unit microreactor) 202 b mayhave a joined body 251 comprising a metal substrate 252 formed on onesurface thereof with a microchannel portion 253 carrying a catalyst C1via a metal oxide film 256, and a metal cover member 254 joined to themetal substrate 252 so as to cover the microchannel portion 253. Insidethe joined body 251, there is formed a flow path 255 composed of themicrochannel portion 253 and the metal cover member 254, and the metaloxide film (insulating film) 256 is formed around the metal substrate252.

Now, using as an example the unit flow path member (unit microreactor)202 b comprising the foregoing joined body 210, a production methodthereof will be described referring to FIG. 28.

In FIG. 28, a microchannel portion 212 is formed on one surface of ametal substrate 211, and a microchannel portion 214 is formed on onesurface of a metal substrate 213 (FIG. 28A). The microchannel portion212, 214 can be formed by forming a resist having a predeterminedpattern on the metal substrate 211, 213 and performing wet etching usingthe resist as a mask, which can make processing by a micromachineunnecessary.

Then, the metal substrates 211 and 213 are joined together such that themicrochannel portion 212 and the microchannel portion 214 confront eachother, to thereby form a joined body 210 (FIG. 28B). Thereby, themicrochannel portion 212 and the microchannel portion 214 confront eachother to form a flow path 215. The foregoing joining between the metalsubstrates 211 and 213 can be carried out by, for example, diffusionbonding, brazing, or the like.

Then, the joined body 210 is anodically oxidized to form a metal oxidefilm (insulating layer) 216 on the whole surfaces including an innerwall surface of the flow path 215, thereby obtaining a unit flow pathmember 202 b (FIG. 28C). The formation of the metal oxide film(insulating film) 216 can be implemented by, in the state where thejoined body 210 is connected to an anode as an external electrode,immersing the joined body 210 in an anode oxidizing solution so as toconfront a cathode and energizing it. Incidentally, if use is made of ametal material disabling anodic oxidation but enabling a boehmitetreatment for the metal substrates 211 and 213, the metal oxide film 216is formed by the boehmite treatment.

Then, a catalyst Cl is applied to the whole inner wall surface of theflow path 215 of the unit flow path member 202 b via the metal oxidefilm (insulating film) 216, thereby obtaining a unit microreactor 202 b(FIG. 28D). The applying of the catalyst C1 to the metal oxide film(insulating film) 216 can be carried out by, for example, pouring acatalyst suspension into the flow path 215 of the joined body 210 tofill it, or immersing the joined body 210 in the catalyst suspension,and thereafter, removing the catalyst suspension from the flow path 215,and drying the joined body 210.

Incidentally, it may also be arranged that, after forming themicrochannel portions 212 and 214 on the metal substrates 211 and 213,the metal substrates 211 and 213 are anodically oxidized to form metaloxide films, then, after polishing to remove the metal oxide filmsexisting on surfaces that will serve as joining surfaces, the metalsubstrates 211 and 213 are joined together, and then, the catalyst C1 isapplied to the metal oxide film.

Then, by providing a heater on the metal oxide film (insulating film)216 on the side of the metal substrate 211, and further, by formingelectrodes for energization and forming a heater protective layer on theheater, a unit microreactor 202 b can be obtained.

As a method of forming the heater, there can be cited a method offorming it by screen printing using a paste containing the foregoingmaterial, a method of forming an applied film using a paste containingthe foregoing material, then patterning it by etching or the like, amethod of forming a thin film by the vacuum deposition method using theforgoing material, then patterning it by etching or the like, oranother. Further, the electrodes for energization can be formed by, forexample, screen printing using a paste containing the foregoingconductive material. Further, the heater protective layer can be formedin a predetermined pattern by, for example, screen printing using apaste containing the foregoing material.

As described above, by applying the catalyst C1 after the formation ofthe joined body 210 having the flow path 215 to obtain the unitmicroreactor 202 b, there is no possibility of deactivation of thecatalyst due to heat in the joining process so that the selection widthof the catalyst is broadened. Further, by preparing a plurality of unitflow path members each having been completed up to the forming processof the metal oxide film (insulating film) 216, it is possible to obtaina unit microreactor having a required function only by applying adesired catalyst.

Incidentally, the unit flow path member (unit microreactor) 202 b havingthe foregoing joined body 241 can be produced likewise by joining themetal cover member 244, instead of the metal substrate 213, to the metalsubstrate 211 in the foregoing production example.

Now, using as an example the unit flow path member (unit microreactor)202 b comprising the foregoing joined body 251, a production methodthereof will be described referring to FIG. 29.

In FIG. 29, a microchannel portion 253 is first formed on one surface ofa metal substrate 252 (FIG. 29A). The formation of the microchannelportion 53 can be implemented like the formation of the foregoingmicrochannel portion 212, 214.

Then, the metal substrate 252 is anodically oxidized to form a metaloxide film 256 on the whole surfaces including the inside of themicrochannel portion 253 (FIG. 29B). Incidentally, if use is made of ametal material disabling anodic oxidation but enabling a boehmitetreatment for the metal substrate 252, the metal oxide film 256 isformed by the boehmite treatment.

Then, a catalyst C1 is applied to the microchannel portion 253 (FIG.29C). This catalyst applying can be implemented by immersing a surface,where the microchannel portion 253 is formed, of the metal substrate 252in a desired catalyst suspension and drying it.

Then, the side, where the microchannel portion 253 is formed, of themetal substrate 252 is subjected to polishing to expose the surface thatwill serve as a joining surface with a metal cover member 254 (FIG.29D). Thereafter, the metal substrate 252 and the metal cover member 254are joined together to form a joined body 251 (FIG. 29E). By thisjoining, a flow path 255 is formed within the joined body 251.

Then, by providing a heater on the metal oxide film (insulating film)256 of the metal substrate 252, and further, by forming electrodes forenergization and forming a heater protective layer on the heater, a unitflow path member (unit microreactor) 202 b can be obtained.

The foregoing embodiments of the microreactors are only examples, andthe present invention is not limited thereto.

[Production Method of Microreactor]

Now, description will be made of a microreactor producing method of thepresent invention.

First Embodiment of Production Method

FIGS. 30 and 31 are process diagrams for describing one embodiment ofthe microreactor producing method of the present invention.

In FIGS. 30 and 31, description will be made using the foregoingmicroreactor 1 as an example. In the production method of the presentinvention, a microchannel portion 3 is first formed on one surface 2 aof a metal substrate 2 (FIG. 30A). This microchannel portion 3 can beformed by forming a resist having a predetermined opening pattern on thesurface 2 a of the metal substrate 2, and etching the metal substrate 2to leave comb-shaped ribs 2A and 2B by wet etching using the resist as amask, which can make processing by a micromachine unnecessary. As amaterial of the metal substrate 2 that is used, there can be cited Al,Si, Ta, Nb, V, Bi, Y, W, Mo, Zr, Hf, or the like which enables anodicoxidation in the next anodic oxidation process.

Then, the metal substrate 2 formed with the microchannel portion 3 isanodically oxidized to form a metal oxide film (insulating film 4) onthe whole surfaces including the inside of the microchannel portion 3(FIG. 30B). The formation of this metal oxide film (insulating film 4)can be implemented by, in the state where the metal substrate 2 isconnected to an anode as an external electrode, immersing the metalsubstrate 2 in an anode oxidizing solution so as to confront a cathodeand energizing it.

Then, a heater 5 is provided on the metal oxide film (insulating film 4)of a surface 2 b, where the microchannel portion 3 is not formed, of themetal substrate 2, and further, electrodes 6 and 6 for energization areformed (FIG. 30C). The heater 5 can be formed using a material such ascarbon paste, nichrome (Ni—Cr alloy), W, or Mo. As a method of formingthe heater 5, there can be cited a method of forming it by screenprinting using a paste containing the foregoing material, a method offorming an applied film using a paste containing the foregoing material,then patterning it by etching or the like, a method of forming a thinfilm by the vacuum deposition method using the forgoing material, thenpatterning it by etching or the like, or another.

On the other hand, the electrodes 6 and 6 for energization can be formedusing a conductive material such as Au, Ag, Pd, or Pd—Ag. For example,they can be formed by screen printing using a paste containing theforegoing conductive material.

Then, a heater protective layer 7 is formed on the heater 5 so as toexpose the electrodes 6 and 6 (FIG. 30D). The heater protective layer 7can be formed using a material such as polyimide or ceramic (Al₂O₃,SiO₂). For example, it can be formed in a pattern having electrodeopening portions 7 a and 7 a by screen printing using a paste containingthe foregoing material.

Then, a catalyst C is applied to the microchannel portion 3 (FIG. 31A).This catalyst applying can be implemented by immersing the surface 2 a,where the microchannel portion 3 is formed, of the metal substrate 2 ina desired catalyst solution.

Then, the metal substrate 2 is polished to expose the surface 2 athereof (FIG. 31B), thereafter, a cover member 8 is joined to the metalsubstrate surface 2 a to thereby obtain the microreactor 1 of thepresent invention (FIG. 31C). For the cover member 8, an Al alloy, a Cualloy, a stainless material, or the like can be used. The joining of thecover member 8 to the metal substrate surface 2 a can be carried out by,for example, diffusion bonding, brazing, or the like. Upon the joining,positioning is carried out so that a feed material inlet 8 a and a gasoutlet 8 b provided in the cover member 8 coincide with both endportions of a flow path of the microchannel portion 3 formed on themetal substrate 2.

In the production method of the present invention, the formation of theheater 5, the electrodes 6 and 6, and the heater protective layer 7 maybe implemented after the joining between the metal substrate 2 and thecover member 8.

Second Embodiment of Production Method

FIGS. 32 and 33 are process diagrams for describing another embodimentof the microreactor producing method of the present invention.

In FIGS. 32 and 33, description will be made using the foregoingmicroreactor 1′ as an example. In the production method of the presentinvention, a microchannel portion 3 is first formed on one surface 2′aof a metal substrate 2′ (FIG. 32A). As the metal substrate 2′, it ispossible to use any of an Al substrate, a Cu substrate, a stainlesssubstrate, or the like. The formation of the microchannel portion 3 canbe implemented like the foregoing formation of the microchannel portion3 onto the metal substrate 2.

Then, an insulating film 4′ is formed on a surface 2′b, where themicrochannel portion 3 is not formed, of the metal substrate 2′ (FIG.32B). The insulating film 4′ can be formed using, for example,polyimide, ceramic (Al₂O₃, SiO₂), or the like. The formation of theinsulating film 4′ can be implemented, for example, by the printingmethod such as screen printing using a paste containing the foregoinginsulating material, or by forming a thin film by the vacuum filmforming method such as sputtering or vacuum deposition using theforegoing insulating material and curing it.

Then, a heater 5 is provided on the insulating film 4′, and further,electrodes 6 and 6 for energization are formed (FIG. 32C). The formationof such a heater 5 and electrodes 6 and 6 can be implemented like thatin the foregoing production method of the microreactor 1.

Then, a heater protective layer 7 is formed on the heater 5 so as toexpose the electrodes 6 and 6 (FIG. 32D). The formation of this heaterprotective layer 7 can be implemented like that in the foregoingproduction method of the microreactor 1.

Then, a catalyst C is applied to the microchannel portion 3 (FIG. 33A).This catalyst applying can be implemented by immersing the surface 2′a,where the microchannel portion 3 is formed, of the metal substrate 2′ ina desired catalyst solution.

Then, the metal substrate 2′ is polished to expose the metal substratesurface 2′a (FIG. 33B), thereafter, a cover member 8 is joined to themetal substrate surface 2′a to thereby obtain the microreactor 1′ of thepresent invention (FIG. 33C). The joining of the cover member 8 can becarried out like that in the foregoing production method of themicroreactor 1.

In the microreactor producing method of the present invention asdescribed above, since the metal substrate is used, the formation of themicrochannel portion does not require the micromachine processing, butcan be easily implemented by a low-priced processing method such asetching to thereby enable reduction in production cost of themicroreactor.

In the production method of the present invention, the formation of theinsulating film 4′, the heater 5, the electrodes 6 and 6, and the heaterprotective layer 7 may be implemented after the joining between themetal substrate 2′ and the cover member 8.

Third Embodiment of Production Method

FIGS. 34 to 38 are process diagrams for describing one embodiment of themicroreactor producing method of the present invention, using theforegoing microreactor 11 as an example. Each of the diagrams is shownin section at a position corresponding to FIG. 6 or 7.

In the production method of the present invention, at the outset, amicrochannel portion 3 is formed on one surface 12 a of a metalsubstrate 12 and a through hole 19 is formed (FIGS. 34A, 34B). A resisthaving a predetermined opening pattern corresponding to the microchannelportion 13 is formed on the surface 12 a of the metal substrate 12,while a resist having an opening pattern for forming the through hole 19is formed on a surface 12 b of the metal substrate 12. Then, themicrochannel portion 13 is formed by half-etching the metal substrate 12from the side of the surface 12 a so as to leave comb-shaped ribs 12Aand 12B by wet etching using the resist as a mask and, simultaneously,the through hole 19 can be formed by double-sided etching. Therefore,the processing by the micromachine is not required. As a material of themetal substrate 12 that is used, there can be cited Al, Si, Ta, Nb, V,Bi, Y, W, Mo, Zr, Hf, or the like which enables anodic oxidation in thenext anodic oxidation process.

Then, the metal substrate 12 formed with the microchannel portion 13 andthe through hole 19 is anodically oxidized to form a metal oxide film(insulating film 14) on the whole surfaces including the inside of themicrochannel portion 13 and the inside of the through hole 19 (FIGS.34C, 34D). The formation of this metal oxide film (insulating film 14)can be implemented by, in the state where the metal substrate 12 isconnected to an anode as an external electrode, immersing the metalsubstrate 12 in an anode oxidizing solution so as to confront a cathodeand energizing it.

Then, a heater 15 is provided on the metal oxide film (insulating film14) of the surface 12 b, where the microchannel portion 13 is notformed, of the metal substrate 12 so as not to close the through hole19, and further, electrodes 16 and 16 for energization are formed (FIGS.35A, 35B). The heater 15 can be formed using a material such as carbonpaste, nichrome (Ni—Cr alloy), W, or Mo. As a method of forming theheater 15, there can be cited a method of forming it by screen printingusing a paste containing the foregoing material, a method of forming anapplied film using a paste containing the foregoing material, thenpatterning it by etching or the like, a method of forming a thin film bythe vacuum deposition method using the forgoing material, thenpatterning it by etching or the like, or another.

On the other hand, the electrodes 16 and 16 for energization can beformed using a conductive material such as Au, Ag, Pd, or Pd—Ag. Forexample, they can be formed by screen printing using a paste containingthe foregoing conductive material.

Then, a heater protective layer 17 is formed on the heater 15 so as toexpose the electrodes 16 and 16 and the through hole 19 (FIGS. 35C,35D). The heater protective layer 17 can be formed using a material suchas polyimide or ceramic (Al₂O₃SiO₂). For example, it can be formed in apattern having electrode opening portions 17 a and 17 a and an openingportion 17 b by screen printing using a paste containing the foregoingmaterial.

Then, a catalyst C1 is applied to the microchannel portion 13 (FIGS.36A, 36B). This catalyst applying can be implemented by immersing thesurface 12 a, where the microchannel portion 13 is formed, of the metalsubstrate 12 in a desired catalyst solution.

Then, the metal substrate 12 is polished to expose the surface 12 athereof that will serve as a joining surface with a metal substrate 22(FIGS. 36C, 36D).

On the other hand, like the foregoing metal substrate 12, a microchannelportion 23 is formed on one surface 22 a of the metal substrate 22 and athrough hole 29 is formed (FIGS. 37A, 37B). Then, the metal substrate 22formed with the microchannel portion 23 and the through hole 29 isanodically oxidized to form a metal oxide film (insulating film 24) onthe whole surfaces including the inside of the microchannel portion 23and the inside of the through hole 29 (FIGS. 37C, 37D).

Then, a catalyst C2 is applied to the microchannel portion 23 (FIGS.38A, 38B). This catalyst applying can be implemented by immersing thesurface 22 a, where the microchannel portion 23 is formed, of the metalsubstrate 22 in a desired catalyst solution.

Then, the metal substrate 22 is polished on both sides thereof to exposethe surface 22 a thereof that will serve as a joining surface with acover member 28 and a surface 22 b of the metal substrate 22 that willserve as a joining surface with the metal substrate 12 (FIGS. 38C, 38D).

Then, the surface 12 a of the foregoing metal substrate 12 and thesurface 22 b of the metal substrate 22 are joined together, and further,the cover member 28 is joined ,to the metal substrate surface 22 a tothereby obtain the microreactor 11 of the present invention. For thecover member 28, it is possible to use an Al alloy, a Cu alloy, astainless material, or the like. The joining between the metal substrate12 and the metal substrate 22 and the joining between the metalsubstrate 22 and the cover member 28 can be carried out by, for example,diffusion bonding, brazing, or the like. Upon the joining, positioningis carried out so that the through hole 29 of the metal substrate 22coincides with an end portion 13 b of a flow path of the microchannelportion 13 formed on the metal substrate 12, and a gas outlet 28 aprovided in the cover member 28 coincides with an end portion 23 b of aflow path of the microchannel portion 23 formed on the metal substrate22.

In the production method of the present invention, the followingprocesses may be employed. First, joining between the foregoing metalsubstrate 12, metal substrate 22, and cover member 28 is carried out.Thereafter, the heater 15, the electrodes 16 and 16, and the heaterprotective layer 17 may be formed on the metal oxide film (insulatingfilm) 14 on the surface 12 b of the metal substrate 12.

Fourth Embodiment of Production Method

FIGS. 39 and 40 are process diagrams for describing another embodimentof the microreactor producing method of the present invention, using theforegoing microreactor 11′ as an example.

In FIGS. 39 and 40, in the production method of the present invention,at the outset, a microchannel portion 13 and a through hole 19 (notillustrated) are formed on one surface 12′a of a metal substrate 12′(FIG. 39A). As the metal substrate 12′, it is possible to use any of anAl substrate, a Cu substrate, a stainless substrate, or the like. Theformation of the microchannel portion 13 and the through hole 19 can beimplemented like the foregoing formation of the microchannel portion 13and the through hole 19 onto the metal substrate 12.

Then, an insulating film 14′ is formed on a surface 12′b, where themicrochannel portion 13 is not formed, of the metal substrate 12′ so asnot to close the through hole 19 (not illustrated) (FIG. 39B). Theinsulating film 14′ can be formed using, for example, polyimide, ceramic(Al₂O₃, SiO₂), or the like. The formation of the insulating film 14′ canbe implemented, for example, by the printing method such as screenprinting using a paste containing the foregoing insulating material, orby forming a thin film by the vacuum film forming method such assputtering or vacuum deposition using the foregoing insulating materialand curing it.

Then, a heater 15 is provided on the insulating film 14′, and further,electrodes 16 and 16 for energization are formed (FIG. 39C). Theformation of such a heater 15 and electrodes 16 and 16 can beimplemented like that in the foregoing production method of themicroreactor 11.

Then, a heater protective layer 17 is formed on the heater 15 so as toexpose the electrodes 16 and 16 and the through hole 19 (notillustrated) (FIG. 39D). The formation of this heater protective layer17 can be implemented like that in the foregoing production method ofthe microreactor 11.

Then, a catalyst C1 is applied to the microchannel portion 13 (FIG.40A). This catalyst applying can be implemented by immersing the surface12′a, where the microchannel portion 13 is formed, of the metalsubstrate 12′ in a desired catalyst solution.

Then, the metal substrate 12′ is polished to expose the metal substratesurface 12′a that will be joined to a metal substrate 22′ (FIG. 40B).

On the other hand, like the foregoing metal substrate 12′, amicrochannel portion 23 is formed on one surface 22′a of the metalsubstrate 22′ and a through hole 29 (not illustrated) is formed, then acatalyst C2 is applied to the microchannel portion 23, and the metalsubstrate 22′ is polished to expose the surface 22′a of the metalsubstrate 22′ that will serve as a joining surface with a cover member28, and a surface 22′b of the metal substrate 22′ that will serve as ajoining surface with the metal substrate 12′ (FIG. 40C).

Then, the surface 12′a of the foregoing metal substrate 12′ and thesurface 22′b of the metal substrate 22′ are joined together, andfurther, the cover member 28 is joined to the metal substrate surface22′a to thereby obtain the microreactor 11′ of the present invention(FIG. 40D). The joining between the metal substrate 12′ and the metalsubstrate 22′ and the joining between the metal substrate 22′ and thecover member 28 can be carried out like those in the foregoingproduction method of the microreactor 11.

In the microreactor producing method of the present invention asdescribed above, since the metal substrates are used, the formation ofthe microchannel portions does not require the micromachine processing,but can be easily implemented by a low-priced processing method such asetching to thereby enable reduction in production cost of themicroreactor.

In the production method of the present invention, the formation of theheater 15, the electrodes 16 and 16, and the heater protective layer 17onto the insulating film 14′ may be implemented after the joiningbetween the metal substrate 12′, the metal substrate 22′, and the covermember 28.

Fifth Embodiment of Production Method

FIGS. 41 and 42 are process diagrams for describing one embodiment ofthe microreactor producing method of the present invention.

In FIGS. 41 and 42, description will be made using the foregoingmicroreactor 101 as an example.

In the production method of the present invention, at the outset, in achannel portion forming process, a microchannel portion 103 is formed onone surface 102 a of a metal substrate 102 (FIG. 41A). This microchannelportion 103 can be formed by forming a resist having a predeterminedopening pattern on the surface 102 a of the metal substrate 102, andetching the metal substrate 102 to leave comb-shaped ribs 102A and 102Bby wet etching using the resist as a mask, which can make processing bya micromachine unnecessary. The microchannel portion 103 that is formedpreferably has a circular arc shape, a semicircular shape, or a U-shapein section, and preferably has no angular portion on the wall surfacealong the fluid flow direction. With such a shape, it is possible toprevent a catalyst from being accumulated at angular portions in a latercatalyst applying process so that uniform catalyst applying is enabled.As a material of the metal substrate 102 that is used, there can becited Al, Si, Ta, Nb, V, Bi, Y, W, Mo, Zr, Hf, or the like which enablesformation of a metal oxide film by anodic oxidation in a subsequentsurface treatment process.

Then, in a joining process, a metal cover member 4 is joined to themetal substrate surface 102 a to form a joined body 115 (FIG. 41B). As amaterial of the metal cover member 104, it is also possible to use Al,Si, Ta, Nb, V, Bi, Y, W, Mo, Zr, Hf, or the like which enables formationof a metal oxide film by anodic oxidation in the next surface treatmentprocess. The joining of the metal cover member 104 to the metalsubstrate surface 102 a can be implemented by, for example, diffusionbonding, brazing, or the like. Upon the joining, positioning is carriedout so that a feed material inlet 104 a and a gas outlet 104 b providedin the cover member 104 coincide with both end portions of a flow pathof the microchannel portion 103 formed on the metal substrate 102. Inthe joined body 115 thus formed, the microchannel portion 103 is coveredwith the metal cover member 104 to form a flow path 105.

Then, in the surface treatment process, the joined body 115 isanodically oxidized to form a metal oxide film (insulating film) 106 onthe whole surfaces including an inner wall surface of the flow path 105(FIG. 41C). The formation of this metal oxide film (insulating film) 106can be implemented by, in the state where the joined body 115 isconnected to an anode as an external electrode, immersing the joinedbody 115 in an anode oxidizing solution so as to confront a cathode andenergizing it.

Then, in the catalyst applying process, a catalyst C is applied to thewhole inner wall surface of the flow path 105 via the metal oxide film(insulating film) 106 (FIG. 42A). The applying of the catalyst C ontothe metal oxide film (insulating film) 106 can be carried out by, forexample, pouring a catalyst suspension into the flow path 105 of thejoined body 115 to fill it, or immersing the joined body 115 in thecatalyst suspension, and thereafter, removing the catalyst suspensionfrom the flow path 105, and drying the joined body 115. In this catalystapplying process, as described above, when the sectional shape of themicrochannel portion 3 is a circular arc shape, a semicircular shape, ora U-shape and no angular portion exists on the wall surface along thefluid flow direction, there exist hardly any angular portions, where thecatalyst tends to be accumulated, within the flow path 105 so thatuniform catalyst applying is enabled. Incidentally, by giving vibrationor rotation to the joined body 115 upon the foregoing drying, moreuniform catalyst applying is made possible.

Then, a heater 107 is provided on the metal oxide film (insulating film)106 on the side of a surface 102 b of the metal substrate 102, andfurther, electrodes 108 and 108 for energization are formed (FIG. 42B).The heater 107 can be formed using a material such as carbon paste,nichrome (Ni—Cr alloy), W, or Mo. As a method of forming the heater 107,there can be cited a method of forming it by screen printing using apaste containing the foregoing material, a method of forming an appliedfilm using a paste containing the foregoing material, then patterning itby etching or the like, a method of forming a thin film by the vacuumdeposition method using the forgoing material, then patterning it byetching or the like, or another.

On the other hand, the electrodes 108 and 108 for energization can beformed using a conductive material such as Au, Ag, Pd, or Pd—Ag. Forexample, they can be formed by screen printing using a paste containingthe foregoing conductive material.

Then, a heater protective layer 109 is formed on the heater 107 so as toexpose the electrodes 108 and 108 (FIG. 42C). The heater protectivelayer 109 can be formed using a material such as polyimide or ceramic(Al₂O₃, SiO₂). For example, it can be formed in a pattern havingelectrode opening portions 109 a and 109 a by screen printing using apaste containing the foregoing material.

In the production method of the present invention, the followingprocesses may be employed. First, the metal substrate 102 formed withthe microchannel portion 103 is anodically oxidized to form the metaloxide film (insulating film) 106 on the whole surfaces. Then, the metaloxide film 106 existing on the surface 102 a that will serve as thejoining surface is polished to be removed, and then the metal substrate102 and the cover member 104 are joined together. Thereafter, thecatalyst C is applied to the metal oxide film 106 serving as the innerwall surface of the flow path 105.

Sixth Embodiment of Production Method

FIGS. 43 and 44 are process diagrams for describing another embodimentof the microreactor producing method of the present invention.

In FIGS. 43 and 44, description will be made using the foregoingmicroreactor 121 as an example.

In the production method of the present invention, at the outset, in achannel portion forming process, a microchannel portion 123 is formed onone surface 122 a of a metal substrate 122 (FIG. 43A). For the metalsubstrate 122 that is used, it is possible to use a material such as Cu,stainless, Fe, or Al which enables formation of a metal oxide film by aboehmite treatment in a later surface treatment process. The formationof the microchannel portion 123 can be implemented like the formation ofthe microchannel portion 103 on the metal plate 102 in the foregoingembodiment.

Then, in a joining process, after forming an insulating film 130 on asurface 122 b, where the microchannel portion 123 is not formed, of themetal substrate 122, a metal cover member 124 is joined to the metalsubstrate surface 122 a where the microchannel portion 123 is formed, tothereby form a joined body 135 (FIG. 43B).

The insulating film 130 can be formed using, for example, polyimide,ceramic (Al₂O₃, SiO₂), or the like. The formation of the insulating film130 can be implemented, for example, by the printing method such asscreen printing using a paste containing the foregoing insulatingmaterial, or by forming a thin film by the vacuum film forming methodsuch as sputtering or vacuum deposition using the foregoing insulatingmaterial and curing it. Incidentally, the formation of the insulatingfilm 130 may be carried out after the joining between the metalsubstrate 122 and the metal cover member 124.

As a material of the metal cover member 124, it is possible to use amaterial such as Cu, stainless, Fe, or Al which enables formation of ametal oxide film by a boehmite treatment in the next surface treatmentprocess. The joining of the metal cover member 124 to the metalsubstrate surface 122 a can be implemented by, for example, diffusionbonding, brazing, or the like. Upon the joining, positioning is carriedout so that a feed material inlet 124 a and a gas outlet 124 b providedin the metal cover member 124 coincide with both end portions of a flowpath of the microchannel portion 123 formed on the metal substrate 122.In the joined body 135 thus formed, the microchannel portion 123 iscovered with the metal cover member 124 to form a flow path 125.

Then, in the surface treatment process, a metal oxide film 126 is formedon an inner wall surface of the flow path 125 of the joined body 135(FIG. 43C). The formation of the metal oxide film 126 can be implementedby the boehmite treatment. For example, it can be implemented by using asuspension with boehmite alumina such as alumina sol being dispersedtherein, and pouring the suspension with a fully lowered viscosity intothe flow path 125, thereafter, drying it to fix a boehmite coating onthe inner surface of the flow path (washcoat process).

Then, in a catalyst applying process, a catalyst C is applied to thewhole inner wall surface of the flow path 125 via the metal oxide film126 (FIG. 44A). The applying of the catalyst C onto the metal oxide film126 can be carried out like the catalyst applying process in theforegoing embodiment. Also in this embodiment, when the sectional shapeof the microchannel portion 123 is a circular arc shape, a semicircularshape, or a U-shape and no angular portion exists on the wall surfacealong the fluid flow direction, there exist hardly any angular portions,where the catalyst tends to be accumulated, within the flow path 125 sothat uniform catalyst applying is enabled. Incidentally, by givingvibration or rotation to the joined body 135 upon drying, more uniformcatalyst applying is made possible.

Then, a heater 127 is provided on the insulating film 130 on the side ofa surface 122 b of the metal substrate 122, and further, electrodes 128and 128 for energization are formed (FIG. 44B). Thereafter, a heaterprotective layer 129 is formed on the heater 127 so as to expose theelectrodes 128 and 128 (FIG. 42C). Materials and forming methods of theheater 127, the electrodes 128 and 128, and the heater protective layer129 can be the same as in the foregoing embodiment.

In the production method of the present invention, the followingprocesses may be employed. First, the metal substrate 122 formed withthe microchannel portion 123 is anodically oxidized to form the metaloxide film (insulating film) 126 on the whole surfaces. Then, the metaloxide film 126 existing on the surface 122 a that will serve as thejoining surface is polished to be removed. Thereafter, the metalsubstrate 122 and the cover member 124 are joined together. Then, thecatalyst C is applied to the metal oxide film 126 serving as the innerwall surface of the flow path 125. Then, the insulating film 130 isformed on the surface 122 b of the metal substrate 122 and, on thisinsulating film 130, the heater 127, the electrodes 128 and 128, and theheater protective layer 129 are formed.

Seventh Embodiment of Production Method

FIGS. 45 and 46 are process diagrams for describing another embodimentof the microreactor producing method of the present invention.

In FIGS. 45 and 46, description will be made using the foregoingmicroreactor 141 as an example.

In the production method of the present invention, at the outset, in achannel portion forming process, a microchannel portion 143 is formed onone surface 142 a of a metal substrate 142, and a microchannel portion145 is formed on one surface 144 a of a metal substrate 144 (FIG. 45A).The microchannel portion 143, 145 can be formed by forming a resisthaving a predetermined opening pattern on the surface 142 a, 144 a ofthe metal substrate 142, 144 and etching the metal substrate 142, 144 toleave comb-shaped ribs 142A and 142B, 144A and 144B by wet etching usingthe resist as a mask, which can make processing by a micromachineunnecessary.

The metal substrates 142 and 144 form a pair of metal substrates whereinpattern shapes of the microchannel portion 143 and the microchannelportion 145 that are formed have a symmetrical relationship with respectto a joining plane (142 a, 144 a) between the metal substrates 142 and144. Further, the microchannel portion 143, 145 preferably has acircular arc shape, a semicircular shape, or a U-shape in section, andpreferably has no angular portion on the wall surface along the fluidflow direction (a turnback portion at each of tip portions of thecomb-shaped ribs 142A and 142B, 144A and 144B is rounded with no angularportion). With such a shape, it is possible to prevent a catalyst frombeing accumulated at angular portions in a later catalyst applyingprocess so that uniform catalyst applying is enabled. As a material ofthe metal substrate 142, 144 that is used, there can be cited Al, Si,Ta, Nb, V, Bi, Y, W, Mo, Zr, Hf, or the like which enables formation ofa metal oxide film by anodic oxidation in a subsequent surface treatmentprocess.

Then, in a joining process, the pair of metal substrates 142 and 144 arejoined together at the surfaces 142 a and 144 a such that themicrochannel portion 143 and the microchannel portion 145 confront eachother, thereby to form a joined body 155 (FIG. 45B).

As described above, the microchannel portion 143 and the microchannelportion 145 have the pattern shapes that are in a symmetricalrelationship. with respect to the joining plane (142 a, 144 a) betweenthe metal substrates 142 and 144. Therefore, by the joining between themetal substrates 142 and 144, the microchannel portion 143 and themicrochannel portion 145 completely confront each other to form a flowpath 146. The shape of an inner wall surface of the flow path 146 isgenerally circular in a section perpendicular to a fluid flow directionof the flow path 146. The foregoing joining between the metal substrates142 and 144 can be carried out by, for example, diffusion bonding,brazing, or the like.

Then, in the surface treatment process, the joined body 155 isanodically oxidized to form a metal oxide film (insulating film) 147 onthe whole surfaces including the inner wall surface of the flow path 146(FIG. 45C). The formation of this metal oxide film (insulating film) 147can be implemented by, in the state where the joined body 155 isconnected to an anode as an external electrode, immersing the joinedbody 155 in an anode oxidizing solution so as to confront a cathode andenergizing it.

Then, in the catalyst applying process, a catalyst C is applied to thewhole inner wall surface of the flow path 146 via the metal oxide film(insulating film) 147 (FIG. 46A). The applying of the catalyst C to themetal oxide film (insulating film) 147 can be carried out by, forexample, pouring a catalyst suspension into the flow path 146 of thejoined body 155 to fill it, or immersing the joined body 155 in thecatalyst suspension, and thereafter, removing the catalyst suspensionfrom the flow path 146, and drying the joined body 155. In this catalystapplying process, as described above, when the sectional shape of themicrochannel portion 143, 145 is a circular arc shape, a semicircularshape, or a U-shape and no angular portion exists on the wall surfacealong the fluid flow direction, there exist hardly any angular portions,where the catalyst tends to be accumulated, within the flow path 146 sothat uniform catalyst applying is enabled. Incidentally, by givingvibration or rotation to the joined body 155 upon the foregoing drying,more uniform catalyst applying is made possible.

Then, a heater 148 is provided on the metal oxide film (insulating film)147 on the side of a surface 142 b of the metal substrate 142, andfurther, electrodes 149 and 149 for energization are formed (FIG. 46B).The heater 148 can be formed using a material such as carbon paste,nichrome (Ni—Cr alloy), W, or Mo. As a method of forming the heater 148,there can be cited a method of forming it by screen printing using apaste containing the foregoing material, a method of forming an appliedfilm using a paste containing the foregoing material, then patterning itby etching or the like, a method of forming a thin film by the vacuumdeposition method using the forgoing material, then patterning it byetching or the like, or another.

On the other hand, the electrodes 149 and 149 for energization can beformed using a conductive material such as Au, Ag, Pd, or Pd—Ag. Forexample, they can be formed by screen printing using a paste containingthe foregoing conductive material.

Then, a heater protective layer 150 is formed on the heater 148 so as toexpose the electrodes 149 and 149 (FIG. 46C). The heater protectivelayer 150 can be formed using a material such as polyimide or ceramic(Al₂O₃, SiO₂). For example, it can be formed in a pattern havingelectrode opening portions 150 a and 150 a by screen printing using apaste containing the foregoing material.

In the production method of the present invention, the followingprocesses may be employed. First, the metal substrate 142, 144 formedwith the microchannel portion 143, 145 is anodically oxidized to formthe metal oxide film (insulating film) 147 on the whole surfaces. Then,the metal oxide film 147 existing on the surface 142 a, 144 a that willserve as the joining surface is polished to be removed. Thereafter, themetal substrate 142 and the metal substrate 144 are joined together.Then, the catalyst C is applied to the metal oxide film 147 serving asthe inner wall surface of the flow path 146.

Eighth Embodiment of Production Method

FIGS. 47 and 48 are process diagrams for describing another embodimentof the microreactor producing method of the present invention.

In FIGS. 47 and 48, description will be made using the foregoingmicroreactor 161 as an example.

In the production method of the present invention, at the outset, in achannel portion forming process, a microchannel portion 163 is formed onone surface 162 a of a metal substrate 162, and a microchannel portion165 is formed on one surface 164 a of a metal substrate 164 (FIG. 47A).The formation of the microchannel portion 163, 165 can be implementedlike the formation of the microchannel portion 143, 145 on the metalsubstrate 142, 144 in the foregoing third embodiment. For the metalsubstrate 162, 164 that is used, it is possible to use a material suchas Cu, stainless, Fe, or Al which enables formation of a metal oxidefilm by a boehmite treatment in a later surface treatment process.

Then, in a joining process, after forming an insulating film 171 on asurface 162 b, where the microchannel portion 163 is not formed, of themetal substrate 162, the pair of metal substrates 162 and 164 are joinedtogether at the surfaces 162 a and 164 a such that the microchannelportion 163 and the microchannel portion 165 confront each other,thereby to form a joined body 175 (FIG. 47B).

The insulating film 171 can be formed using, for example, polyimide,ceramic (Al₂O₃, SiO₂), or the like. The formation of the insulating film171 can be implemented, for example, by the printing method such asscreen printing using a paste containing the foregoing insulatingmaterial, or by forming a thin film by the vacuum film forming methodsuch as sputtering or vacuum deposition using the foregoing insulatingmaterial and curing it. Incidentally, the formation of the insulatingfilm 171 may be carried out after the joining between the metalsubstrates 162 and 164.

The joining of the foregoing metal substrates 162 and 164 can beimplemented by, for example, diffusion bonding, brazing, or the like. Inthis joining, since the microchannel portion 163 and the microchannelportion 165 have pattern shapes that are in a symmetrical relationshipwith respect to a joining plane (162 a, 164 a) between the metalsubstrates 162 and 164, the microchannel portion 163 and themicrochannel portion 165 completely confront each other to form a flowpath 166. The shape of an inner wall surface of the flow path 166 isgenerally circular in a section perpendicular to a fluid flow directionof the flow path 166.

Then, in the surface treatment process, a metal oxide film 167 is formedon an inner wall surface of the flow path 166 of the joined body 175(FIG. 47C). The formation of the metal oxide film 167 can be implementedby the boehmite treatment. For example, it can be implemented by using asuspension with boehmite alumina such as alumina sol being dispersedtherein, and pouring the suspension with a fully lowered viscosity intothe flow path 166, thereafter, drying it to fix a boehmite coating onthe inner surface of the flow path (washcoat process).

Then, in a catalyst applying process, a catalyst C is applied to thewhole inner wall surface of the flow path 166 via the metal oxide film167 (FIG. 48A). The applying of the catalyst C to the metal oxide film167 can be carried out like the catalyst applying process in theforegoing third embodiment. Also in this embodiment, when the sectionalshape of the microchannel portion 163, 165 is a circular arc shape, asemicircular shape, or a U-shape and no angular portion exists on thewall surface along the fluid flow direction, an angular portion, wherethe catalyst tends to be accumulated, does not exist within the flowpath 166 so that uniform catalyst applying is enabled. Incidentally, bygiving vibration or rotation to the joined body 175 upon drying, moreuniform catalyst applying is made possible.

Then, a heater 168 is provided on the insulating film 171 on the side ofa surface 162 b of the metal substrate 162, and further, electrodes 169and 169 for energization are formed (FIG. 48B). Thereafter, a heaterprotective layer 170 is formed on the heater 168 so as to expose theelectrodes 169 and 169 (FIG. 48C). Materials and forming methods of theheater 168, the electrodes 169 and 169, and the heater protective layer170 can be the same as in the foregoing third embodiment.

In the production method of the present invention, the followingprocesses may be employed. First, the metal substrate 162, 164 formedwith the microchannel portion 163, 165 is anodically oxidized to formthe metal oxide film (insulating film) 167 on the whole surfaces. Then,the metal oxide film 167 existing on the surface 162 a, 164 a that willserve as the joining surface is polished to be removed. Thereafter, themetal substrate 162 and the metal substrate 164 are joined together.Then, the catalyst C is applied to the metal oxide film 167 serving asthe inner wall surface of the flow path 166.

In the microreactor producing method of the present invention asdescribed above, since the catalyst is applied after the joined bodyhaving the flow path therein is formed in the joining process, there isno possibility of deactivation of the catalyst due to heat in thejoining process so that the selection width of the catalyst isbroadened. Further, by preparing a plurality of joined bodies throughcompletion up to the joining process and applying desired catalysts inthese joined bodies, it is possible to produce microreactors to be usedin different reactions, for example, microreactors for reformingmethanol and for oxidation of carbon monoxide, and therefore,simplification of the production processes is made possible. Further,since the metal substrate is used, the formation of the microchannelportion does not require the micromachine processing, but can be easilyimplemented by a low-priced processing method such as etching, andfurther, the polishing process is also unnecessary, so that reduction inproduction cost of the microreactor can be achieved. Further, if it isconfigured such that no angular portion exists on the inner wall surfaceof the flow path, dispersion of the applying amount in the catalystapplying process is suppressed so that the catalyst can be uniformlyapplied.

The foregoing embodiments of the microreactor producing methods are onlyexamples, and the present invention is not limited thereto.

Now, the present invention will be described in further detail showingmore specific examples.

EXAMPLE 1

An Al substrate (250 mm×250 mm) having a thickness of 1000 μm wasprepared as a base member, and a photosensitive resist material (OFPRproduced by Tokyo Ohka Kogyo Co., Ltd.) was applied (film thickness 7 μm(dried)) to both surfaces of the Al substrate by the dip method. Then,on the resist film on the side, where a microchannel portion was to beformed, of the Al substrate, there was disposed a photomask having ashape in which stripe-shaped light-shielding portions each having awidth of 1500 μm projected (projecting length 30 mm) alternately fromright and left at pitches of 2000 μm. Then, the resist film was exposedvia the photomask and developed using a sodium bicarbonate solution. Asa result, on one surface of the Al substrate, there was formed a resistpattern in which stripe-shaped opening portions each having a width of500 μm were arrayed at pitches of 2000 μm, and the adjacentstripe-shaped opening portions were alternately continuous with eachother at their end portions.

Then, using the foregoing resist pattern as a mask, the Al substrate wassubjected to etching under the following condition. This etching was forforming a microchannel portion by half etching from the one surface ofthe Al substrate, and a time required for the etching was three minutes.

(Etching Condition)

-   -   Temperature: 20° C.    -   Etching Liquid (HCl) Concentration: 200 g/L        -   (one liter containing pure water and 200 g of 35% HCl            dissolved therein)

After the foregoing etching process was finished, the resist pattern wasremoved using a sodium hydroxide solution and washing was carried out.As a result, on the one surface of the Al substrate, there was formed amicrochannel portion (flow path length 300 mm) wherein stripe-shapedmicrochannels each having a width of 1000 μm, a depth of 650 μm, and alength of 30 mm were formed at pitches of 2000 μm so as to bealternately continuous with each other at end portions of the adjacentmicrochannels (as shown in FIG. 3).

Then, the foregoing Al substrate was connected to an anode as anexternal electrode, immersed in an anode oxidizing solution (4% oxalicacid solution) so as to confront a cathode, and energized under thefollowing condition, to thereby obtain an aluminum oxide thin filmformed as an insulating film. The thickness of the formed aluminum oxidethin film was measured by an ellipsometer, and the result was about 30μm.

(Anodic Oxidation Condition)

-   -   Bath Temperature: 25° C.    -   Voltage: 25V (DC)    -   Current Density: 100 A/m²

Then, on the aluminum oxide thin film, where the microchannel portionwas not formed, of the Al substrate, a paste for heater having thefollowing composition was printed by screen printing, then cured at 200°C. to form a heater. The formed heater had a shape in which a fine linehaving a width of 100 μm was drawn around on the Al substrate at lineintervals of 100 μm so as to cover the whole of a region (35 mm×25 mm)corresponding to a region where the microchannel portion was formed.

(Composition of Paste for Heater)

Carbon Powder 20 weight parts Fine Powder Silica 25 weight parts XylenePhenol Resin 36 weight parts Butyl Carbitol 19 weight parts

Further, using a paste for electrode having the following composition,electrodes (0.5 mm×0.5 mm) were formed at predetermined two portions ofthe heater by screen printing.

(Composition of Paste for Electrode)

Silver-plated Copper Powder  90 weight parts Phenol Resin 6.5 weightparts Butyl Carbitol 3.5 weight parts

Then, using a paste for protective layer having the followingcomposition, a heater protective layer (thickness 20 μm) was formed onthe heater by screen printing so as to expose the two electrodes formedon the heater.

(Composition of Paste for Protective Layer)

Resin Concentration 30 weight parts Silica Filler 10 weight partsLactone Solvent 60 weight parts (penta-1,4-lactone)

Then, the side, where the microchannel portion was formed, of the Alsubstrate was immersed (10 minutes) in a catalyst aqueous solutionhaving the following composition, then was subjected to a dry/reductiontreatment at 250° C. for six hours, thereby applying a catalyst in themicrochannel portion.

(Composition of Catalyst Aqueous Solution)

Al 41.2 weight %  Cu 2.6 weight % Zn 2.8 weight %

Then, the side, where the microchannel portion was formed, of the Alsubstrate was polished by alumina powder to thereby expose the Alsurface. Then, as a cover member, an Al plate having a thickness of 100μm was diffusion bonded to the Al substrate surface under the followingcondition. This Al plate was provided with two opening portions (a feedmaterial inlet and a gas outlet: size of each opening portion 0.6 mm×0.6mm), and positioning was carried out so that the opening portionscoincided with both end portions of a flow path of the microchannelportion formed on the Al substrate.

(Diffusion Bonding Condition)

-   -   Atmosphere: Under Vacuum    -   Bonding Temperature: 300° C.    -   Bonding Time: 8 Hours

Consequently, a microreactor of the present invention was obtained.

EXAMPLE 2

[Production of First-Step Metal Substrate]

A stainless substrate (SUS304, 250 mm×250 mm) having a thickness of 1000μm was prepared as a base member, and a photosensitive resist material(OFPR produced by Tokyo Ohka Kogyo Co., Ltd.) was applied (filmthickness 7 μm (dried)) to both surfaces of the stainless substrate bythe dip method. Then, on the resist film on the side, where amicrochannel portion was to be formed, of the stainless substrate, therewas disposed a photomask having a shape in which stripe-shapedlight-shielding portions each having a width of 1500 μm projected(projecting length 30 mm) alternately from right and left at pitches of2000 μm. Further, a photomask having a circular opening with an openingdiameter of 800 μm was disposed on the other resist film. Then, theresist films were exposed via those photomasks and developed using asodium bicarbonate solution. As a result, on one surface of thestainless substrate, there was formed a resist pattern in whichstripe-shaped opening portions each having a width of 500 μm werearrayed at pitches of 2000 μm, and the adjacent stripe-shaped openingportions were alternately continuous with each other at their endportions. On the other surface of the stainless substrate, there wasformed a resist pattern having a circular opening with an openingdiameter of 800 μm. This circular opening was located at a positioncorresponding to a predetermined position of the stripe-shaped openingportion on the opposite surface.

Then, using the foregoing resist patterns as masks, the stainlesssubstrate was subjected to etching under the following condition. Thisetching was for forming a microchannel portion by half etching from theone surface of the stainless substrate, and for forming a through holeby etching from the other surface. A time required for the etching was25 minutes.

(Etching Condition)

-   -   Temperature: 80° C.    -   Etching Liquid (ferric chloride solution)        -   Specific Weight: 45 (° B′e)

After the foregoing etching process was finished, the resist patternswere removed using a sodium hydroxide solution and washing was carriedout. As a result, on the one surface of the stainless substrate, therewas formed a microchannel portion (flow path length 300 mm) whereinstripe-shaped microchannels each having a width of 1000 μm, a depth of650 μm, and a length of 30 mm were formed at pitches of 2000 μm so as tobe alternately continuous with each other at end portions of theadjacent microchannels (as shown in FIG. 9). Further, as shown in FIG.9, an opening of the formed through hole was located at an end portionof the continuous microchannel portion.

Then, on the stainless substrate surface where the microchannel portionwas not formed, a polyimide precursor solution (Photoneece produced byToray Industries, Inc.) as an application liquid for insulating film wasprinted by screen printing so as not to close the foregoing throughhole, then cured at 350° C. to thereby form an insulating film having athickness of 20 μm.

Then, a paste for heater having the following composition was printed byscreen printing on the insulating film of the stainless substrate, thencured at 200° C. to form a heater. The formed heater had a shape inwhich a fine line having a width of 100 μm was drawn around on theinsulating film at line intervals of 100 μm so as to cover the whole ofa region (35 mm×25 mm) corresponding to a region where the microchannelportion was formed, and so as not to close the through hole.

(Composition of Paste for Heater)

Carbon Powder 20 weight parts Fine Powder Silica 25 weight parts XylenePhenol Resin 36 weight parts Butyl Carbitol 19 weight parts

Further, using a paste for electrode having the following composition,electrodes (0.5 mm×0.5 mm) were formed at predetermined two portions ofthe heater by screen printing.

(Composition of Paste for Electrode)

Silver-plated Copper Powder  90 weight parts Phenol Resin 6.5 weightparts Butyl Carbitol 3.5 weight parts

Then, using a paste for protective layer having the followingcomposition, a heater protective layer (thickness 20 μm) was formed onthe heater by screen printing so as to expose the two electrodes formedon the heater and the opening of the through hole.

(Composition of Paste for Protective Layer)

Resin Concentration 30 weight parts Silica Filler 10 weight partsLactone Solvent 60 weight parts (penta-1,4-lactone)

Then, the side, where the microchannel portion was formed, of thestainless substrate was immersed (10 minutes) in a catalyst aqueoussolution having the following composition, then was subjected to adry/reduction treatment at 250° C. for six hours, thereby applying acatalyst in the microchannel portion.

(Composition of Catalyst Aqueous Solution)

Al 41.2 weight %  Cu 2.6 weight % Zn 2.8 weight %

Then, the side, where the microchannel portion was formed, of thestainless substrate was polished by alumina powder to thereby expose thestainless substrate surface. Consequently, the first-step metalsubstrate was prepared.

[Production of Second-Step Metal Substrate]

On the other hand, the same stainless substrate as described above wasprepared, and photosensitive resist films were formed on both surfacesof the stainless substrate in the same manner as described above. Then,on the resist film on the side, where a microchannel portion was to beformed, of the stainless substrate, there was disposed a photomaskhaving a shape in which stripe-shaped light-shielding portions eachhaving a width of 1500 μm projected (projecting length 30 mm)alternately from right and left at pitches of 2000 μm. Further, aphotomask having a circular opening with an opening diameter of 800 μmwas disposed on the other resist film. Then, the resist films wereexposed via those photomasks and developed using a sodium bicarbonatesolution. As a result, on one surface of the stainless substrate, therewas formed a resist pattern in which stripe-shaped opening portions eachhaving a width of 500 μm were arrayed at pitches of 2000 m, and theadjacent stripe-shaped opening portions were alternately continuous witheach other at their end portions. On the other surface of the stainlesssubstrate, there was formed a resist pattern having a circular openingwith an opening diameter of 800 μm. This circular opening was located ata position corresponding to a predetermined position of thestripe-shaped opening portion on the opposite surface.

Then, using the foregoing resist patterns as masks, the stainlesssubstrate was subjected to etching under the same condition as describedabove. This etching was for forming a microchannel portion by halfetching from the one surface of the stainless substrate, and for forminga through hole by etching from the other surface. A time required forthe etching was 25 minutes.

After the foregoing etching process was finished, the resist patternswere removed using a sodium hydroxide solution and washing was carriedout. As a result, on the one surface of the stainless substrate, therewas formed a microchannel portion (flow path length 300 mm) whereinstripe-shaped microchannels each having a width of 1000 μm, a depth of650 μm, and a length of 30 mm were formed at pitches of 2000 μm so as tobe alternately continuous with each other at end portions of theadjacent microchannels (as shown in FIG. 10). Further, as shown in FIG.10, an opening of the formed through hole was located at an end portionof the continuous microchannel portion.

Then, the side, where the microchannel portion was formed, of thestainless substrate was immersed (10 minutes) in a catalyst aqueoussolution having the following composition, then was subjected to adry/reduction treatment at 500° C. for one hour, thereby applying acatalyst to the microchannel portion.

(Composition of Catalyst Aqueous Solution)

Pt 0.4 weight % Fe 0.2 weight % Mordenite 9.4 weight %[Na₈(Al₈Si₄₀O₉₆)•24H₂O]

Then, the side, where the microchannel portion was formed, of thestainless substrate was polished by alumina powder to thereby expose thestainless substrate surface. Consequently, the second-step metalsubstrate was prepared.

[Joining Process]

The surface, where the microchannel portion was formed, of the foregoingfirst-step metal substrate, and the surface, opposite to the surfacewhere the microchannel portion was formed, of the second-step metalsubstrate were diffusion bonded together under the following condition.Upon this bonding, positioning was carried out so that the through holeof the second-step metal substrate coincides with the end portion of theflow path of the microchannel portion formed on the first-step metalsubstrate (the end portion different from the end portion where thethrough hole of the first-step metal substrate was formed).

(Diffusion Bonding Condition)

-   -   Atmosphere: Under Vacuum    -   Bonding Temperature: 1000° C.    -   Bonding Time: 12 Hours

Then, as a cover member, a stainless plate having a thickness of 0.3 μmwas diffusion bonded to the surface, where the microchannel portion wasformed, of the second-step metal substrate under the followingcondition. This stainless plate was provided with one opening portion (agas outlet: size of the opening portion 0.6 mm×0.6 mm), and positioningwas carried out so that the opening portion coincided with the endportion of the flow path of the microchannel portion formed on thesecond-step metal substrate (the end portion different from the endportion where the through hole of the second-step metal substrate wasformed).

(Diffusion Bonding Condition)

-   -   Atmosphere: Under Vacuum    -   Bonding Temperature: 1000° C.    -   Bonding Time: 12 Hours

Consequently, a microreactor of the present invention was obtained.

EXAMPLE 3

An Al substrate (250 mm×250 mm) having a thickness of 1000 μm wasprepared as a metal substrate, and a photosensitive resist material(OFPR produced by Tokyo Ohka Kogyo Co., Ltd.) was applied (filmthickness 7 μm (dried)) to both surfaces of the Al substrate by the dipmethod. Then, on the resist film on the side, where a microchannelportion was to be formed, of the Al substrate, there was disposed aphotomask having a shape in which stripe-shaped light-shielding portionseach having a width of 1500 μm projected (projecting length 30 mm)alternately from right and left at pitches of 2000 μm. In thisphotomask, a portion where each of the foregoing stripe-shapedlight-shielding portions projected from a base portion did not form anangle of 90°, but formed an R-shape with a radius of 1750 μm. Then, theresist film was exposed via the photomask and developed using a sodiumbicarbonate solution. As a result, on one surface of the Al substrate,there was formed a resist pattern in which stripe-shaped openingportions each having a width of 500 μm were arrayed at pitches of 2000μm, and the adjacent stripe-shaped opening portions were alternatelycontinuous with each other at their end portions.

Then, using the foregoing resist pattern as a mask, the Al substrate wassubjected to etching (3 minutes) under the following condition.

(Etching Condition)

-   -   Temperature: 20° C.    -   Etching Liquid (HCl) Concentration: 200 g/L        -   (one liter containing pure water and 200 g of 35% HCl            dissolved therein)

After the foregoing etching process was finished, the resist pattern wasremoved using a sodium hydroxide solution and washing was carried out.As a result, on the one surface of the Al substrate, there was. formed amicrochannel portion (flow path length 300 mm) having a shape whereinstripe-shaped microchannels each having a width of 1000 μm, a depth of650 μm, and a length of 30 mm were formed at pitches of 2000 μm so as tobe alternately continuous with each other at end portions of theadjacent microchannels (the shape continuously meandering while turningback by 180 degrees, as shown in FIG. 14). Turnback portions of themicrochannel portion each had roundness with no angular portion, and noangular portion existed on an inner wall surface along a fluid flowdirection. Further, the shape of the inner wall surface of themicrochannel portion was generally semicircular in a sectionperpendicular to the fluid flow direction.

Then, an Al plate having a thickness of 100 μm was prepared as a metalcover member. This Al plate was diffusion bonded to the Al substrateformed with the microchannel portion as described above so as to coverthe microchannel portion under the following condition, to therebyproduce a joined body. This Al plate was provided with two openingportions (a feed material inlet and a gas outlet: size of each openingportion 0.6 mm×0.6 mm), and positioning was carried out so that theopening portions coincided with both end portions of a flow path of themicrochannel portion formed on the Al substrate. Consequently, the flowpath connecting between the feed material inlet and the gas outlet wasformed within the joined body.

(Diffusion Bonding Condition)

-   -   Atmosphere: Under Vacuum    -   Bonding Temperature: 300° C.    -   Bonding Time: 8 Hours

Then, the foregoing joined body was connected to an anode as an externalelectrode, immersed in an anode oxidizing solution (4% oxalic acidsolution) so as to confront a cathode, and energized under the followingcondition, to thereby form an aluminum oxide thin film, serving as aninsulating film, on the surfaces of the joined body including the insideof the flow path. The thickness of the formed aluminum oxide thin filmwas measured by an ellipsometer, and the result was about 30 μm.

(Anodic Oxidation Condition)

-   -   Bath Temperature: 25° C.    -   Voltage: 25V (DC)    -   Current Density: 100 A/m²

Then, a catalyst suspension having the following composition was filledinto the flow path of the joined body and left standing (15 minutes).Then, the catalyst suspension was removed, and a dry/reduction treatmentwas carried out at 120° C. for three hours to thereby apply a catalystover the whole surface within the flow path.

(Composition of Catalyst Suspension)

Al 41.2 weight %  Cu 2.6 weight % Zn 2.8 weight %

Then, on the aluminum oxide thin film, where the microchannel portionwas not formed, of the Al substrate, a paste for heater having thefollowing composition was printed by screen printing, then cured at 200°C. to form a heater. The formed heater had a shape in which a fine linehaving a width of 100 μm was drawn around on the Al substrate at lineintervals of 100 μm so as to cover the whole of a region (35 mm×25 mm)corresponding to a region where the microchannel portion was formed.

(Composition of Paste for Heater)

Carbon Powder 20 weight parts Fine Powder Silica 25 weight parts XylenePhenol Resin 36 weight parts Butyl Carbitol 19 weight parts

Further, using a paste for electrode having the following composition,electrodes (0.5 mm×0.5 mm) were formed at predetermined two portions ofthe heater by screen printing.

(Composition of Paste for Electrode)

Silver-plated Copper Powder  90 weight parts Phenol Resin 6.5 weightparts Butyl Carbitol 3.5 weight parts

Then, using a paste for protective layer having the followingcomposition, a heater protective layer (thickness 20 μm) was formed onthe heater by screen printing so as to expose the two electrodes formedon the heater.

(Composition of Paste for Protective Layer)

Resin Concentration 30 weight parts Silica Filler 10 weight partsLactone Solvent 60 weight parts (penta-1,4-lactone)

Consequently, a microreactor of the present invention was obtained.

EXAMPLE 4

An Al substrate (250 mm×250 mm) having a thickness of 1000 μm wasprepared as a metal substrate, and a photosensitive resist material(OFPR produced by Tokyo Ohka Kogyo Co., Ltd.) was applied (filmthickness 7 μm (dried)) to both surfaces of the Al substrate by the dipmethod. Then, on the resist film on the side, where a microchannelportion was to be formed, of the Al substrate, there was disposed aphotomask having a shape in which stripe-shaped light-shielding portionseach having a width of 1500 μm projected (projecting length 30 mm)alternately from right and left at pitches of 2000 μm. In thisphotomask, a portion where each of the foregoing stripe-shapedlight-shielding portions projected from a base portion did not form anangle of 90°, but formed an R-shape with a radius of 1750 μm. The sameAl substrate as described above was prepared, the photosensitive resistmaterial was applied in the same manner, and a photomask was disposed onthe resist film on the side, where a microchannel portion was to beformed, of the Al substrate. This photomask was configured to beplane-symmetrical with the foregoing photomask with respect to the Alsubstrate surface.

Then, with respect to the foregoing pair of metal substrates, the resistfilms were exposed via the photomasks, respectively, and developed usinga sodium bicarbonate solution. As a result, on one surface of each Alsubstrate, there was formed a resist pattern in which stripe-shapedopening portions each having a width of 500 μm were arrayed at pitchesof 2000 μm, and the adjacent stripe-shaped opening portions werealternately continuous with each other at their end portions.

Then, using the foregoing resist pattern as a mask, the Al substrate wassubjected to etching (3 minutes) under the following condition.

(Etching Condition)

-   -   Temperature: 20° C.    -   Etching Liquid (HCl) Concentration: 200 g/L        -   (one liter containing pure water and 200 g of 35% HCl            dissolved therein)

After the foregoing etching process was finished, the resist pattern wasremoved using a sodium hydroxide solution and washing was carried out.As a result, on the one surface of each of the pair of Al substrates,there was formed a microchannel portion (flow path length 300 mm) havinga shape wherein stripe-shaped microchannels each having a width of 1000μm, a depth of 650 μm, and a length of 30 mm were formed at pitches of2000 μm so as to be alternately continuous with each other at endportions of the adjacent microchannels (the shape continuouslymeandering while turning back by 180 degrees, as shown in FIG. 18).Turnback portions of the microchannel portion each had roundness with noangular portion, and no angular portion existed on an inner wall surfacealong a fluid flow direction. Further, the shape of the inner wallsurface of the microchannel portion was generally semicircular in asection perpendicular to the fluid flow direction.

Then, the foregoing pair of Al substrates were diffusion bonded togetherunder the following condition so that the mutual microchannel portionsconfront each other, thereby producing a joined body. Upon this bonding,positioning was carried out so that the microchannel portions of thepair of Al substrates completely confront each other. Consequently,within the joined body, there was formed a flow path having a feedmaterial inlet and a gas outlet that are located at one end surface ofthe joined body.

(Diffusion Bonding Condition)

-   -   Atmosphere: Under Vacuum    -   Bonding Temperature: 300° C.    -   Bonding Time: 8 Hours

Then, the foregoing joined body was connected to an anode as an externalelectrode, immersed in an anode oxidizing solution (4% oxalic acidsolution) so as to confront a cathode, and energized under the followingcondition, to thereby form an aluminum oxide thin film, serving as aninsulating film, on the surfaces of the joined body including the insideof the flow path. The thickness of the formed aluminum oxide thin filmwas measured by an ellipsometer, and the result was about 30 μm.

(Anodic Oxidation Condition)

-   -   Bath Temperature: 25° C.    -   Voltage: 25V (DC)    -   Current Density: 100A/m²

Then, a catalyst suspension having the following composition was filledinto the flow path of the joined body and left standing (15 minutes).Then, the catalyst suspension was removed, and a dry/reduction treatmentwas carried out at 120° C. for three hours to thereby apply a catalystover the whole surface within the flow path.

(Composition of Catalyst Suspension)

Al 41.2 weight %  Cu 2.6 weight % Zn 2.8 weight %

Then, a heater, electrodes, and a heater protective layer were formed,like in Example 3, on the aluminum oxide thin film of one of the Alsubstrates.

Consequently, a microreactor of the present invention was obtained.

EXAMPLE 5

A SUS304 substrate (250 mm×250 mm) having a thickness of 1000 μm wasprepared as a metal substrate, and a photosensitive resist material(OFPR produced by Tokyo Ohka Kogyo Co., Ltd.) was applied (filmthickness 7 μm (dried)) to both surfaces of the SUS304 substrate by thedip method. Then, on the resist film on the side, where a microchannelportion was to be formed, of the SUS304 substrate, there was disposed aphotomask having a shape in which stripe-shaped light-shielding portionseach having a width of 1500 μm projected (projecting length 30mm)alternately from right and left at pitches of 2000 μm. In thisphotomask, a portion where each of the foregoing stripe-shapedlight-shielding portions projected from a base portion did not form anangle of 90°, but formed an R-shape with a radius of 1750 μm. The sameSUS304 substrate as described above was prepared, the photosensitiveresist material was applied in the same manner, and a photomask wasdisposed on the resist film on the side, where a microchannel portionwas to be formed, of the SUS304 substrate. This photomask was configuredto be plane-symmetrical with the foregoing photomask with respect to theSUS304 substrate surface.

Then, with respect to the foregoing pair of metal substrates (SUS304substrates), the resist films were exposed via the photomasks,respectively, and developed using a sodium bicarbonate solution. As aresult, on one surface of each SUS304 substrate, there was formed aresist pattern in which stripe-shaped opening portions each having awidth of 500 μm were arrayed at pitches of 2000 μm, and the adjacentstripe-shaped opening portions were alternately continuous with eachother at their end portions.

Then, using the foregoing resist pattern as a mask, the SUS304 substratewas subjected to etching (3 minutes) under the following condition.

(Etching Condition)

-   -   Temperature: 80° C.    -   Etching Liquid (ferric chloride solution)        -   Specific Weight Concentration: 45 (° B′e)

After the foregoing etching process was finished, the resist pattern wasremoved using a sodium hydroxide solution and washing was carried out.As a result, on the one surface of each of the pair of SUS304substrates, there was formed a microchannel portion (flow path length300 mm) having a shape wherein stripe-shaped microchannels each having awidth of 1000 μm, a depth of 650 μm, and a length of 30 mm were formedat pitches of 2000 μm so as to be alternately continuous with each otherat end portions of the adjacent microchannels (the shape continuouslymeandering while turning back by 180 degrees, as shown in FIG. 18).Turnback portions of the microchannel portion each had roundness with noangular portion, and no angular portion existed on an inner wall surfacealong a fluid flow direction. Further, the shape of the inner wallsurface of the microchannel portion was generally semicircular in asection perpendicular to the fluid flow direction.

Then, the pair of SUS304 substrates comprising this SUS304 substrate andthe other SUS304 substrate were diffusion bonded together under thefollowing condition so that the mutual microchannel portions confronteach other, thereby producing a joined body. Upon this bonding,positioning was carried out so that the microchannel portions of thepair of SUS304 substrates completely confront each other. Consequently,within the joined body, there was formed a flow path having a feedmaterial inlet and a gas outlet that are located at one end surface ofthe joined body.

(Diffusion Bonding Condition)

-   -   Atmosphere: Under Vacuum    -   Bonding Temperature: 1000° C.    -   Bonding Time: 12 Hours

Then, on the surface, where the microchannel portion was not formed, ofone of the SUS304 substrates forming the foregoing joined body, apolyimide precursor solution (Photoneece produced by Toray Industries,Inc.) as an application liquid for insulating film was printed by screenprinting, then cured at 350° C. to thereby form an insulating filmhaving a thickness of 20 μm.

Then, a boehmite treatment was applied to the inner wall surface of theflow path of the foregoing joined body under the following condition toform an aluminum oxide thin film. The thickness of the formed aluminumoxide thin film was measured by an ellipsometer, and the result wasabout 5 μm.

(Condition of Boehmite Treatment)

Aluminasol 520 (produced by Nissan Chemical Industries, Ltd.) was usedto prepare an alumina sol suspension with a viscosity of 15 to 20 mPa·s.Then, this alumina sol suspension was poured into the flow path of thejoined body, and drying was carried out at 120° C. for three hours tothereby fix a boehmite film inside the flow path.

Then, a catalyst was applied over the whole surface in the flow path ofthe joined body like in Example 4. Thereafter, a heater, electrodes, anda heater protective layer were formed, like in Example 3, on theinsulating film formed on one of the SUS304 substrates.

Consequently, a microreactor of the present invention was obtained.

EXAMPLE 6

[Production of Joined Body]

An Al substrate (250 mm×250 mm) having a thickness of 1000 μm wasprepared as a metal substrate, and a photosensitive resist material(OFPR produced by Tokyo Ohka Kogyo Co., Ltd.) was applied (filmthickness 7 μm (dried)) to both surfaces of the Al substrate by the dipmethod. Then, on the resist film on the side, where a microchannelportion was to be formed, of the Al substrate, there was disposed aphotomask having a shape in which stripe-shaped light-shielding portionseach having a width of 1500 μm extended (length 30 mm) alternately fromright and left at pitches of 2000 μm. Then, the resist film was exposedvia the photomask and developed using a sodium bicarbonate solution. Asa result, on one surface of the Al substrate, there was formed a resistpattern in which stripe-shaped opening portions each having a width of500 μm were arrayed at pitches of 2000 μm and the adjacent stripe-shapedopening portions were alternately continuous with each other at theirend portions to thereby provide a zigzag pattern, and further, both endportions are oriented in the same direction and are longer than theother stripe-shaped opening portions by 5 mm.

Then, using the foregoing resist pattern as a mask, the Al substrate wassubjected to etching (3 minutes) under the following condition.

(Etching Condition)

-   -   Temperature: 20° C.    -   Etching Liquid (HCl) Concentration: 200 g/L        -   (one liter containing pure water and 200 g of 35% HCl            dissolved therein)

After the foregoing etching process was finished, the resist pattern wasremoved using a sodium hydroxide solution and washing was carried out.As a result, on the one surface of the Al substrate, there was formed amicrochannel portion (flow path length 300 mm) having a shape whereinstripe-shaped microchannels each having a width of 1000 μm, a depth of650 μm, and a length of 30 mm were formed at pitches of 2000 μm so as tobe alternately continuous with each other at end portions of theadjacent microchannels (the shape continuously meandering while turningback by 180 degrees, as shown in FIG. 23).

Then, an Al plate having a thickness of 100 μm was prepared as a metalcover member. This Al plate was diffusion bonded to the Al substrateformed with the microchannel portion as described above so as to coverthe microchannel portion under the following condition.

(Diffusion Bonding Condition)

-   -   Atmosphere: Under Vacuum    -   Bonding Temperature: 300° C.    -   Bonding Time: 8 Hours

Consequently, there was formed a joined body having an external shape asshown in FIG. 22. This joined body had a size of 25 mm×35 mm and athickness of 1.4 mm, and had two projecting portions (length 5 mm, width5 mm) in the same direction which were apart from each other by adistance of 15 mm. An inlet and an outlet of a flow path were located atthe tips of the projecting portions.

Three such joined bodies were produced. Each of the joined bodies wasconnected to an anode as an external electrode, immersed in an anodeoxidizing solution (4% oxalic acid solution) so as to confront acathode, and energized under the following condition, to thereby obtaina unit flow path member formed with an aluminum oxide thin film(insulating film) on the surfaces of the joined body including theinside of the flow path. The thickness of the formed aluminum oxide thinfilm was measured by an ellipsometer, and the result was about 30 μm.

(Anodic Oxidation Condition)

-   -   Bath Temperature: 25° C.    -   Voltage: 25V (DC)    -   Current Density: 100 A/m²        [First-Step Unit Flow Path Member]

On the aluminum oxide thin film of one unit flow path member, a pastefor heater having the following composition was printed by screenprinting, then cured at 200° C. to form a heater. The formed heater hada shape in which a fine line having a width of 100 μm was drawn aroundon the Al substrate at line intervals of 100 μm so as to cover the wholeof a region (35 mm×25 mm) corresponding to a region where themicrochannel portion was formed.

(Composition of Paste for Heater)

Carbon Powder 20 weight parts Fine Powder Silica 25 weight parts XylenePhenol Resin 36 weight parts Butyl Carbitol 19 weight parts

Further, using a paste for electrode having the following composition,electrodes were formed at predetermined two portions of the heater byscreen printing so as to reach side surfaces of the joined body.

(Composition of Paste for Electrode)

Silver-plated Copper Powder  90 weight parts Phenol Resin 6.5 weightparts Butyl Carbitol 3.5 weight parts

Then, using a paste for protective layer having the followingcomposition, a heater protective layer (thickness 20 μm) was formed onthe heater by screen printing so as to expose end portions of the twoelectrodes formed on the heater.

(Composition of Paste for Protective Layer)

Resin Concentration 30 weight parts Silica Filler 10 weight partsLactone Solvent 60 weight parts (penta-1,4-lactone)

Consequently, a first-step unit flow path member was obtained.

[Second-Step Unit Flow Path Member (Unit Microreactor)]

A catalyst suspension having the following composition was filled intothe flow path of another unit flow path member and left standing (15minutes). Then, the catalyst suspension was removed, and a dry/reductiontreatment was carried out at 120° C. for three hours to thereby apply acatalyst C1 over the whole surface within the flow path.

(Composition of Catalyst Suspension)

Al 41.2 weight %  Cu 2.6 weight % Zn 2.8 weight %

Then, like the foregoing first-step unit flow path member, a heater,electrodes, and a heater protective layer were formed on the aluminumoxide thin film of the Al substrate to produce a second-step unit flowpath member (unit microreactor).

[Third-Step Unit Flow Path Member (Unit Microreactor)]

A catalyst suspension having the following composition was filled intothe flow path of another unit flow path member and left standing (15minutes). Then, the catalyst suspension was removed, and a dry/reductiontreatment was carried out at 120° C. for three hours to thereby apply acatalyst C2 over the whole surface within the flow path.

(Composition of Catalyst Suspension)

Pt 0.4 weight % Fe 0.2 weight % Mordenite 9.4 weight %(Na₈(Al₈Si₄₀O₉₆)•24H₂O)

Then, like the foregoing first-step unit flow path member, a heater,electrodes, and a heater protective layer were formed on the aluminumoxide thin film of the Al substrate to produce a third-step unit flowpath member (unit microreactor).

[Production of Coupling Member]

Six stainless plates having flat surfaces (30 mm×20 mm) were prepared.Predetermined grooves and through holes for constituting couplingportions, internal communication paths, internal flow paths, and thelike were formed on either flat surfaces of the respective stainlessplates by mechanical processing. By diffusion bonding these sixstainless plates in a predetermined stacking order to unify them, acoupling member of 30 mm×20 mm×12 mm was produced. This coupling memberhad a structure as shown in FIGS. 24 and 25 (the external shape of thestructure body was a rectangular parallelepiped and thus different fromFIGS. 24 and 25), wherein six coupling portions (width 5.1 mm, height1.41 mm, depth 5 mm) were provided on the surface of 30 mm×12 mm, a feedmaterial inlet and a gas outlet were provided on the surface oppositethereto, and the internal communication paths and the internal flowpaths were provided inside. In this coupling member, the pitch of thethree coupling portions arrayed in a row (corresponding to the pitch ofthe multi-steps of the unit flow path members) was 2 mm, and thedistance between the array rows (corresponding to the distance betweenan inlet and an outlet of the unit flow path member) was 20 mm.Incidentally, a packing made of silicon rubber was mounted in each ofthe coupling portions.

[Production of Fixing Member]

Using stainless members, there was produced a fixing member havingaccommodation spaces each with a frontage of 25 mm×1.41 mm in threesteps at pitches of 2 mm.

[Production of Microreactor]

Projecting portions of the respective unit flow path members (the secondand third steps were unit microreactors) were inserted into and coupledto the coupling member produced as described above, in proper order fromthe first step to the third step, and end portions of the respectiveunit flow path members opposite to their coupled end portions were fixedby the fixing member.

Consequently, a microreactor of the present invention was obtained.

EXAMPLE 7

Like in Example 1, a microchannel portion was formed on the Alsubstrate.

Then, like in Example 1, an aluminum oxide thin film was formed on theAl substrate by anodic oxidation.

Then, the side, where the microchannel portion was formed, of the Alsubstrate was immersed (2 hours) in a catalyst aqueous solution havingthe following composition, then was subjected to a dry/reductiontreatment at 350° C. for one hour, thereby applying a catalyst to themicrochannel portion.

(Composition of Catalyst Aqueous Solution)

Al 41.2 weight %  Cu 2.6 weight % Zn 2.8 weight %

Then, the side, where the microchannel portion was formed, of the Alsubstrate was polished by alumina powder to thereby expose the Alsurface. Then, as a cover member, an Al plate having a thickness of 100μm was joined to the Al substrate surface by brazing under the followingcondition. This Al plate was provided with two opening portions (a feedmaterial inlet and a gas outlet: size of each opening portion 0.6 mm×0.6mm), and positioning was carried out so that the opening portionscoincided with both end portions of a flow path of the microchannelportion formed on the Al substrate.

(Brazing Condition)

-   -   Brazing Material: Alumi 4004 (produced by Furukawa-Sky Aluminum        Corp.)    -   Atmosphere: Under Vacuum    -   Brazing Temperature: 600° C.    -   Brazing Time: 3 Minutes

Then, a heater, electrodes, and a heater protective layer were formed,like in Example 1, on the aluminum oxide thin film of the joined Alsubstrate.

Consequently, a microreactor of the present invention was obtained.

EXAMPLE 8

[Production of First-Step Metal Substrate]

Like in [Production of First-Step Metal Substrate] of Example 2, on onesurface of a stainless substrate was formed a microchannel portion (flowpath length 300 mm) wherein stripe-shaped microchannels each having awidth of 1000 μm, a depth of 650 μm, and a length of 30 mm were formedat pitches of 2000 μm so as to be alternately continuous with each otherat end portions of the adjacent microchannels (as shown in FIG. 9).Further, as shown in FIG. 9, an opening of a formed through hole waslocated at an end portion of the continuous microchannel portion.

Then, the side, where the microchannel portion was formed, of thestainless substrate was immersed (2 hours) in a catalyst aqueoussolution having the following composition, then was subjected to adry/reduction treatment at 350° C. for one hour, thereby applying acatalyst to the microchannel portion.

(Composition of Catalyst Aqueous Solution)

Al 41.2 weight %  Cu 2.6 weight % Zn 2.8 weight %

Then, the side, where the microchannel portion was formed, of thestainless substrate was polished by alumina powder to thereby expose thestainless substrate surface. Consequently, a first-step metal substratewas prepared.

[Production of Second-Step Metal Substrate]

Like in [Production of Second-Step Metal Substrate] of Example 2, on onesurface of a stainless substrate was formed a microchannel portion (flowpath length 300 mm) wherein stripe-shaped microchannels each having awidth of 1000 μm, a depth of 650 μm, and a length of 30 mm were formedat pitches of 2000 μm so as to be alternately continuous with each otherat end portions of the adjacent microchannels (as shown in FIG. 10).Further, as shown in FIG. 10, an opening of a formed through hole waslocated at an end portion of the continuous microchannel portion.

Then, the side, where the microchannel portion was formed, of thestainless substrate was immersed (10 minutes) in a catalyst aqueoussolution having the following composition, then was subjected to adry/reduction treatment at 500° C. for one hour, thereby applying acatalyst to the microchannel portion.

(Composition of Catalyst Aqueous Solution)

Pt 0.4 weight % Fe 0.2 weight % Mordenite 9.4 weight %[Na₈(Al₈Si₄₀O₉₆)•24H₂O]

Then, the side, where the microchannel portion was formed, of thestainless substrate was polished by alumina powder to thereby expose thestainless substrate surface. Consequently, a second-step metal substratewas prepared.

[Joining Process]

The surface, where the Microchannel portion was formed, of the foregoingfirst-step metal substrate, and the surface, opposite to the surfacewhere the microchannel portion was formed, of the second-step metalsubstrate were diffusion bonded together under the same condition as inExample 2.

Then, as a cover member, a stainless plate having a thickness of 0.3 μmwas diffusion bonded to the surface, where the microchannel portion wasformed, of the second-step metal substrate under the same condition asin Example 2. This stainless plate was provided with one opening portion(a gas outlet: size of the opening portion 0.6 mm×0.6 mm), andpositioning was carried out so that the opening portion coincided withan end portion of a flow path of the microchannel portion formed on thesecond-step metal substrate (an end portion different from an endportion where a through hole of the second-step metal substrate wasformed).

Then, an insulating film, a heater, electrodes, and a heater protectivelayer were formed, like in Example 2, on the first-step metal substratesurface.

Consequently, a microreactor of the present invention was obtained.

EXAMPLE 9

First, like in Example 3, on one surface of an Al substrate was formed amicrochannel portion (flow path length 300 mm) having a shape whereinstripe-shaped microchannels each having a width of 1000 μm, a depth of650 μm, and a length of 30 mm were formed at pitches of 2000 μm so as tobe alternately continuous with each other at end portions of theadjacent microchannels (the shape continuously meandering while turningback by 180 degrees, as shown in FIG. 14).

Then, the foregoing Al substrate was connected to an anode as anexternal electrode and, under the same condition as in Example 3, analuminum oxide thin film was formed on the Al substrate surfacesincluding the microchannel portion to serve as an insulating film. Then,the joining side (the side where the microchannel portion was formed) ofthe Al substrate was polished by alumina powder to remove the aluminumoxide thin film, thereby to expose the Al substrate.

Then, an Al plate having a thickness of 100 μm was prepared as a metalcover member. This Al plate was brazed to the Al substrate formed withthe aluminum oxide thin film in the microchannel portion as describedabove so as to cover the microchannel portion, to thereby produce ajoined body. This Al plate was provided with two opening portions (afeed material inlet and a gas outlet: size of each opening portion 0.6mm×0.6 mm), and positioning was carried out so that the opening portionscoincided with both end portions of a flow path of the microchannelportion formed on the Al substrate. Consequently, the flow pathconnecting between the feed material inlet and the gas outlet was formedwithin the joined body. The brazing condition was the same as that inExample 7.

Then, a catalyst suspension having the same composition as in Example 3was filled in the flow path of the joined body to thereby apply acatalyst over the whole surface in the flow path under the samecondition as in Example 3.

Then, a heater, electrodes, and a heater protective layer were formed,like in Example 3, on the aluminum oxide thin film of the Al substratewhere the microchannel portion was not formed.

Consequently, a microreactor of the present invention was obtained.

EXAMPLE 10

First, like in Example 4, there were produced a pair of Al substrateshaving microchannel portions that are plane-symmetrical with each other.

Then, each of the foregoing Al substrates was connected to an anode asan external electrode and, under the same condition as in Example 4, analuminum oxide thin film was formed on the Al substrate surfacesincluding the microchannel portion to serve as an insulating film. Then,the aluminum oxide thin film existing on the joining surface of each Alsubstrate was polished by alumina powder to be removed, thereby toexpose the Al substrate.

Then, the foregoing pair of Al substrates were joined by brazing so thatthe mutual microchannel portions confront each other, thereby producinga joined body. Upon this joining, positioning was carried out so thatthe microchannel portions of the pair of Al substrates completelyconfront each other. Consequently, within the joined body, there wasformed a flow path having a feed material inlet and a gas outlet thatare located at one end surface of the joined body. The brazing conditionwas the same as that in Example 7.

Then, a catalyst suspension having the same composition as in Example 4was filled in the flow path of the joined body to thereby apply acatalyst over the whole surface in the flow path under the samecondition as in Example 4.

Then, a heater, electrodes, and a heater protective layer were formed,like in Example 3, on the aluminum oxide thin film of one of the Alsubstrates.

Consequently, a microreactor of the present invention was obtained.

EXAMPLE 11

First, like in Example 5, there were produced a pair of SUS304substrates having microchannel portions that are plane-symmetrical witheach other.

Then, a boehmite treatment was applied to the surface, where themicrochannel portion was formed, of each of the foregoing SUS304substrates under the same condition as in Example 5, to thereby form analuminum oxide thin film. Then, the aluminum oxide thin film existing onthe joining surface of each SUS304 substrate was polished by aluminapowder to be removed, thereby to expose the SUS304 substrate.

Then, this pair of SUS304 substrates were diffusion bonded togetherunder the same condition as in Example 5 so that the mutual microchannelportions confront each other, thereby producing a joined body. Upon thisbonding, positioning was carried out so that the microchannel portionsof the pair of SUS304 substrates completely confront each other.Consequently, within the joined body, there was formed a flow pathhaving a feed material inlet and a gas outlet that are located at oneend surface of the joined body.

Then, a catalyst was applied over the whole surface in the flow path ofthe joined body like in Example 4. Thereafter, an insulating film wasformed, like in Example 5, on one of the SUS304 substrates. On thisinsulating film, a heater, electrodes, and a heater protective layerwere formed like in Example 3.

Consequently, a microreactor of the present invention was obtained.

EXAMPLE 12

[Production of Joined Body]

First, like in [Production of Joined Body] of Example 6, there wasproduced an Al substrate in which stripe-shaped microchannels eachhaving a width of 1000 μm, a depth of 650 μm, and a length of 30 mm wereformed at pitches of 2000 μm.

Then, this Al substrate was connected to an anode as an externalelectrode, and subjected to anodic oxidation under the same condition asin Example 6 to thereby form an aluminum oxide thin film (insulatingfilm) on the Al substrate surfaces including the microchannel portion.Then, the surface where the microchannel portion was formed was polishedby alumina powder to remove the aluminum oxide thin film, therebyexposing the Al substrate surface (joining surface).

Then, an Al plate having a thickness of 100 μm was prepared as a metalcover member. This Al plate was brazed, under the same condition as inExample 6, to the Al substrate formed with the microchannel portion asdescribed above so as to cover the microchannel portion. Consequently,three joined bodies each having an external shape as shown in FIG. 22were produced to serve as unit flow path members. This joined body had asize of 25 mm×35 mm and a thickness of 1.4 mm, and had two projectingportions (length 5 mm, width 5 mm) in the same direction which wereapart from each other by a distance of 15 mm. An inlet and an outlet ofa flow path were located at the tips of the projecting portions.

Using the foregoing three unit flow path members, a first-step unit flowpath member, a second-step unit flow path member, and a third-step unitflow path member were produced, thereby producing a microreactor of thepresent invention.

INDUSTRIAL APPLICABILITY

The present invention can be utilized for hydrogen production achievedfrom reactions such as reforming of methanol and oxidation of carbonmonoxide.

1. A microreactor for obtaining hydrogen gas by reforming a feedmaterial, comprising: a metal substrate having a microchannel portion onone surface thereof, an insulating film formed on an other surface ofthe metal substrate where the microchannel portion is not formed, aheater provided on the insulating film on the other surface of saidmetal substrate such that a front surface of the heater contacts theinsulating film and a back surface of the heater includes a heaterprotective layer that covers said heater while exposing only electrodesextending from the back surface of the heater, the electrodes beingconfigured to energize the heater, a catalyst supported on saidmicrochannel portion, and a cover member having a feed material inletand a gas outlet and joined to said metal substrate so as to cover saidmicrochannel portion to form a single continuous flow path, wherein thefeed material inlet and the gas outlet are substantially perpendicularto axial directions of the single continuous flow path.
 2. Amicroreactor according to claim 1, wherein said metal substrate is oneof an Al substrate, a Cu substrate, and a stainless substrate.
 3. Amicroreactor according to claim 1, wherein said insulating film is ametal oxide film formed by anodically oxidizing said metal substrate. 4.A microreactor according to claim 3, wherein said metal oxide film isalso provided in said microchannel portion.
 5. A microreactor accordingto claim 4, wherein said metal substrate is an Al substrate.
 6. Aproduction method of a microreactor for obtaining hydrogen gas byreforming a feed material, comprising: forming a microchannel portion onone surface of a metal substrate; anodically oxidizing said metalsubstrate to form an insulating film in the form of a metal oxide film;providing a heater on said metal oxide film on an other surface, wheresaid microchannel portion is not formed, of said metal substrate suchthat a front surface of the heater contacts the insulating film and aback surface of the heater includes a heater protective layer thatcovers said heater while exposing only electrodes extending from theback surface of the heater, the electrodes being configured to energizethe heater; applying a catalyst to said microchannel portion; andjoining a cover member formed with a feed material inlet and a gasoutlet to said metal substrate so as to cover said microchannel portionto form a single continuous flow path, wherein the feed material inletand the gas outlet are substantially perpendicular to axial directionsof the single continuous flow path.
 7. A production method of amicroreactor for obtaining hydrogen gas by reforming a feed material,comprising: forming a microchannel portion on one surface of a metalsubstrate; providing an insulating film on an other surface, where saidmicrochannel portion is not formed, of said metal substrate; providing aheater on said insulating film such that a front surface of the heatercontacts the insulating film and a back surface of the heater includes aheater protective layer that covers said heater while exposing onlyelectrodes extending from the back surface of the heater, the electrodesbeing configured to energize the heater; applying a catalyst to saidmicrochannel portion; and joining a cover member formed with a feedmaterial inlet and a gas outlet to said metal substrate so as to coversaid microchannel portion to form a single continuous flow path, whereinthe feed material inlet and the gas outlet are substantiallyperpendicular to axial directions of the single continuous flow path. 8.A microreactor for obtaining hydrogen gas by reforming a feed material,comprising: a joined body comprising a metal substrate provided with amicrochannel portion on one surface thereof, and a metal cover memberhaving a feed material inlet and a gas outlet and joined to said metalsubstrate so as to cover said microchannel portion to form a singlecontinuous flow path, the single continuous flow path formed by saidmicrochannel portion located inside said joined body and said metalcover member, a catalyst supported on a whole inner wall surface of saidflow path, an insulating film formed on an other surface of the metalsubstrate where the microchannel portion is not formed, and a heaterprovided on the insulating film on the other surface such that a frontsurface of the heater contacts the insulating film and a back surface ofthe heater includes a heater protective layer that covers said heaterwhile exposing only electrodes extending from the back surface of theheater, the electrodes being configured to energize the heater, whereinthe feed material inlet and the gas outlet are substantiallyperpendicular to axial directions of the single continuous flow path. 9.A microreactor according to claim 8, wherein said flow path has noangular portion on the inner wall surface along a fluid flow direction.10. A microreactor according to claim 8, wherein the catalyst issupported on the inner wall surface of said flow path via a metal oxidefilm.
 11. A microreactor according to claim 10, wherein said metal oxidefilm is formed by anodic oxidation of said metal substrate and saidmetal cover member.
 12. A microreactor according to claim 10, whereinsaid metal oxide film is formed by a boehmite treatment.
 13. Aproduction method of a microreactor for obtaining hydrogen gas byreforming a feed material, comprising: forming a microchannel portion onone surface of a metal substrate; joining a metal cover member having afeed material inlet and a gas outlet to said metal substrate so as tocover said microchannel portion to thereby form a joined body having asingle continuous flow path, wherein the feed material inlet and the gasoutlet are substantially perpendicular to axial directions of the singlecontinuous flow path; forming a metal oxide film on an inner wallsurface of said flow path; applying a catalyst to the inner wall surfaceof said flow path via said metal oxide film; and providing a heater onan insulating film formed on an other surface, where said microchannelportion is not formed, of said metal substrate such that a front surfaceof the heater contacts the insulating film and a back surface of theheater includes a heater protective layer that covers said heater whileexposing only electrodes extending from the back surface of the heater,the electrodes being configured to energize the heater.
 14. A productionmethod of a microreactor according to claim 13, wherein said forming themetal oxide film forms said metal oxide film by anodically oxidizingsaid metal substrate and said metal cover member.
 15. A productionmethod of a microreactor according to claim 13, wherein said forming themetal oxide film forms said metal oxide film by a boehmite treatment.